Kohler SV470, SV620, SV480, SV530, SV540 Service Manual

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Page 1

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Contents

Section 1. Safety and General Information .............................................................................

Section 2. Tools & Aids .............................................................................................................

Section 3. Troubleshooting ......................................................................................................

Section 4. Air Cleaner and Air Intake System .........................................................................

Section 5. Fuel System and Governor .....................................................................................

Section 6. Lubrication System .................................................................................................

Section 7. Electrical System and Components ......................................................................

Section 8. Disassembly.............................................................................................................

Section 9. Inspection and Reconditioning ..............................................................................

Section 10. Reassembly............................................................................................................

Section 11. Emission Compliance Systems............................................................................

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Safety and General Information

Section 1

Safety and General Information

Safety Precautions

To ensure safe operation please read the following statements and understand their meaning. Also refer to your equipment manufacturer's manual for other important safety information. This manual contains safety precautions which are explained below. Please read carefully.

WARNING

Warning is used to indicate the presence of a hazard that can cause severe personal injury, death, or substantial property damage if the warning is ignored.

CAUTION

Caution is used to indicate the presence of a hazard that will or can cause minor personal injury or property damage if the caution is ignored.

Section 1

NOTE

Note is used to notify people of installation, operation, or maintenance information that is important but not hazard-related.

For Your Safety!

These precautions should be followed at all times. Failure to follow these precautions could result in injury to yourself and others.

WARNING

Accidental Starts can cause severe injury or death.

Disconnect and ground spark plug leads before servicing.

Accidental Starts!

ȱǯȱȱ ȱȱȱȱ¢ȱȱ ǯȱBefore working on the engine

or equipment, disable the engine as follows: 1) Disconnect the spark plug lead(s). 2) Disconnect negative (-) baery cable from baery.

WARNING

Rotating Parts can cause severe injury.

Stay away while engine is in operation.

Rotating Parts!

Keep hands, feet, hair, and clothing away from all moving parts to prevent injury. Never operate the engine with covers, shrouds, or guards removed.

Hot Parts can cause severe burns.

Do not touch engine while operating or just aer stopping.

Hot Parts!

Engine components can get extremely hot from operation. To prevent severe burns, do not touch these areas while the engine is running, or immediately aer it is turned oﬀ. Never operate the engine with heat shields or guards removed.

WARNING

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Section 1 Safety and General Information

WARNING

Explosive Fuel can cause ﬁres and severe burns.

Do not ﬁll the fuel tank while the engine is hot or running.

Explosive Fuel!

Gasoline is extremely ﬂammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well ventilated, unoccupied buildings, away from sparks or ﬂames. Do not ﬁll the fuel tank while the engine is hot or running, since spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Do not start the engine near spilled fuel. Never use gasoline as a cleaning agent.

WARNING

Carbon Monoxide can cause severe nausea, fainting or death.

Avoid inhaling exhaust fumes, and never run the engine in a closed building or conﬁned area.

Lethal Exhaust Gases!

Engine exhaust gases contain poisonous carbon monoxide. Carbon monoxide is odorless, colorless, and can cause death if inhaled. Avoid inhaling exhaust fumes, and never run the engine in a closed building or conﬁned area.

WARNING

Explosive Gas can cause ﬁres and severe acid burns.

Charge baery only in a well ventilated area. Keep sources of ignition away.

Explosive Gas!

Baeries produce explosive hydrogen gas while being charged. To prevent a ﬁre or explosion, charge baeries only in well ventilated areas. Keep sparks, open ﬂames, and other sources of ignition away from the baery at all times. Keep baeries out of the reach of children. Remove all jewelry when servicing baeries.

Before disconnecting the negative (-) ground cable, make sure all switches are OFF. If ON, a spark will occur at the ground cable terminal which could cause an explosion if hydrogen gas or gasoline vapors are present.

Cleaning Solvents can cause severe injury or death.

Use only in well ventilated areas away from ignition sources.

Flammable Solvents!

Carburetor cleaners and solvents are extremely ﬂammable. Keep sparks, ﬂames, and other sources of ignition away from the area. Follow the cleaner manufacturer’s warnings and instructions on its proper and safe use. Never use gasoline as a cleaning agent.

1.2

CAUTION

Electrical Shock can cause injury.

Do not touch wires while engine is running.

Electrical Shock!

Never touch electrical wires or components while the engine is running. They can be sources of electrical shock.

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Engine Identiﬁcation Numbers

When ordering parts, or in any communication involving an engine, always give the Model, Speciﬁcation, and Serial Numbers of the engine.

The engine identiﬁcation numbers appear on a decal aﬃxed to the engine shrouding. See Figure 1-1. An explanation of these numbers is shown in Figure 1-2.

Section 1

Safety and General Information

Identiﬁcation Decal

Figure 1-1. Engine Identiﬁcation Decal Location.

A. Model No. Courage Vertical Shaft Engine

Numerical Designation

B. Spec. No. Engine Model

Model  69

  69   69   69   69   69   69   69

C. Serial No.

Year Manufactured Code

Code Year

                           

SV 540 S

Version Code

6 (OHFWULF6WDUW

SV540-0001

First spec written in this model series

3205810334

Factory Code

Figure 1-2. Explanation of Engine Identiﬁcation Numbers.

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Section 1 Safety and General Information

Oil Recommendations

Using the proper type and weight of oil in the crankcase is extremely important, as is checking oil daily and changing oil regularly. Failure to use the correct oil or using dirty oil causes premature engine wear and failure.

Oil Type

Use high-quality detergent oil of API (American Petroleum Institute) service class SJ or higher. Select

the viscosity based on the air temperature at the time of operation as shown below.

RECOMMENDED SAE VISCOSITY GRADES

10W-30

5W-20, 5W-30

°F -20 0 20 32 40 60 80 100

°C -30 -20 -10 0 10 20 30 40

TEMPERATURE RANGE EXPECTED BEFORE NEXT OIL CHANGE

* Use of synthetic oil having 5W-20 or 5W-30 rating is acceptable,

up to 4°C (40°F)

** Synthetic oils will provide better starting in extreme cold below

23°C (-10°F)

NOTE: Using other than service class SJ or higher

oil or extending oil change intervals longer than recommended can cause engine damage.

NOTE: Synthetic oils meeting the listed

classiﬁcations may be used with oil changes performed at the recommended intervals. However to allow piston rings to properly seat, a new or rebuilt engine should be operated for at least 50 hours using standard petroleum based oil before switching to synthetic oil.

A logo or symbol on oil containers identiﬁes the API service class and SAE viscosity grade. See Figure 1-3.

Figure 1-3. Oil Container Logo.

SAE

10W-30

Kohler 10W-30

Refer to Section 6 - Lubrication System for detailed oil check, oil change, and oil ﬁlter change procedures.

Fuel Recommendations

WARNING: Explosive Fuel!

General Recommendations

Purchase gasoline in small quantities and store

in clean, approved containers. A container with a capacity of 2 gallons or less with a pouring spout is recommended. Such a container is easier to handle and helps eliminate spillage during refueling.

Do not use gasoline le over from the previous season, to minimize gum deposits in your fuel system and to ensure easy starting.

Do not add oil to the gasoline.

Do not overﬁll the fuel tank. Leave room for the fuel to expand.

Fuel Type

For best results use only clean, fresh, unleaded gasoline with a pump sticker octane rating of 87 (R+M)/2 or higher. In countries using the Research Octane Number (RON), it should be 90 octane

minimum. Leaded gasoline is not recommended and must not be used on EFI engines or on other models where exhaust emissions are regulated.

Gasoline/Alcohol Blends

Gasohol (up to 10% ethyl alcohol, 90% unleaded gasoline by volume) is approved as a fuel for Kohler engines. Other gasoline/alcohol blends including E20 and E85 are not to be used and not approved. Any failures resulting from use of these fuels will not be warranted.

Gasoline/Ether Blends

Methyl Tertiary Butyl Ether (MTBE) and unleaded gasoline blends (up to a maximum of 15% MTBE by volume) are approved as a fuel for Kohler engines. Other gasoline/ether blends are not approved.

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Periodic Maintenance

Section 1

Safety and General Information

WARNING: Accidental Starts!

ȱǯȱȱȱȱȱȱ¢ȱȱǯȱBefore working on the engine or equipment, disable the engine as follows: 1) Disconnect the spark plug lead(s). 2) Disconnect negative (-) baery cable from baery.

Maintenance Schedule

Normal maintenance, replacement or repair of emission control devices and systems may be performed by any repair establishment or individual; however, warranty repairs must be performed by a Kohler authorized

service center.

Maintenance RequiredFrequency

• Fill fuel tank.

Daily or Before

Starting Engine

Annually

or Every 25 Hours

Annually or

Every 100 Hours

Every 200 Hours

• Check oil level.

• Check air cleaner for dirty¹, loose, or damaged parts.

• Check air intake and cooling areas, clean as necessary¹.

• Service precleaner element¹ (if equipped).

• Service air cleaner element¹ (if not equipped with precleaner).

• Replace air cleaner element¹ (if equipped with precleaner).

• Change oil and ﬁlter (more frequently under severe conditions).

• Remove cooling shroud and clean cooling areas.

• Check that all fasteners are in place and components are properly secured.

• Replace fuel ﬁlter.

• Check spark plug condition and gap.

• Have valve lash checked/adjusted2.

Every 500 Hours

¹Perform these maintenance procedures more frequently under extremely dusty, dirty conditions. ²Have a Kohler Engine Service Dealer perform this service.

Storage

If the engine will be out of service for two months or more, use the following storage procedure:

1. Clean the exterior surfaces of the engine.

2. Change the oil and oil ﬁlter while the engine is still warm from operation. See Change Oil and Oil Filter in Section 6.

3. The fuel system must be completely emptied, or the gasoline must be treated with a stabilizer to prevent deterioration. If you choose to use a stabilizer, follow the manufacturer’s recommendations, and add the correct amount for the capacity of the fuel system. Fill the fuel tank with clean, fresh gasoline. Run the engine for 2-3 minutes to get stabilized fuel into the carburetor.

• Have bendix starter drive serviced².

• Replace spark plug.

To empty the system, run the engine until the

tank and system are empty.

4. Due to the deep recess around the spark plug, blow out the cavity with compressed air. Remove the spark plug. The spark plug is most accessible when the blower housing is removed for cleaning.

Add one tablespoon of engine oil into the spark

plug hole. Install the plug, but do not connect the plug lead. Crank the engine two or three revolutions. Connect the plug lead.

5. Reinstall the blower housing, if removed previously, and torque the blower housing screws to 7.5 N·m (65 in. lb.).

6. Store the engine in a clean, dry place.

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Section 1 Safety and General Information

VALVE COVER VIEW

Dimensions in millimeters. Inch equivalents shown in ().

Figure 1-4. Typical Engine Dimensions.

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Page 11

Safety and General Information

General Speciﬁcations¹

Power (@ 3600 RPM, exceeds Society of Automotive Engineers-Small Engine Test Code J1940)

SV470 ............................................................................................................. 11.2 kW (15 HP)

SV480 ............................................................................................................. 11.9 kW (16 HP)

SV530 ............................................................................................................. 12.7 kW (17 HP)

SV540 .............................................................................................................. 13.4 kW (18 HP)

SV590 ............................................................................................................. 14.1 kW (19 HP)

SV600 .............................................................................................................. 14.9 kW (20 HP)

SV610 .............................................................................................................. 15.7 kW (21 HP)

SV620 .............................................................................................................. 16.4 kW (22 HP)

Bore

SV470, SV480 (Early Models Only) ............................................................. 84 mm (3.30 in.)

SV470, SV480, SV530, SV540 ........................................................................89 mm (3.50 in.)

SV590, SV600, SV610, SV620 ........................................................................94 mm (3.70 in.)

Stroke ...................................................................................................................... 86 mm (3.38 in.)

Displacement

SV470, SV480 (Early Models Only) ............................................................. 477 cc (29.1 cu. in.)

SV470, SV480, SV530, SV540 ........................................................................535 cc (32.6 cu. in.)

SV590, SV600, SV610, SV620 ........................................................................597 cc (36.4 cu. in.)

Section 1

Compression Ratio

SV470, SV480, SV530, SV540 ........................................................................9.4:1

SV590, SV600, SV610, SV620 ........................................................................8.5:1

Dry Weight .............................................................................................................35.8 kg (79 lb.)

Oil Capacity (with ﬁlter) .....................................................................................1.04-1.30 L (1.1-1.4 qt.)

Angle of Operation - Maximum (at Full Oil Level) All Directions ...............25° Intermient

Air Cleaner Base

Hex Nut Fastener Torque .................................................................................... 5.5 N·m (48 in. lb.)

Mounting Screw Fastener Torque (Install Dry - DO NOT OIL) ....................8.0 N·m (70 in. lb.) Into new as-cast hole

5.5 N·m (48 in. lb.) Into used hole

Blower Housing and Sheet Metal

M6 Fasteners Torque ..................................................................11.6 N·m (99 in. lb.) Into new as-cast hole

7.7 N·m (68 in. lb.) Into used hole

Cam Lever

Cam Lever Fastener Torque ...................................................... 8.0-10.5 N·m (70-94.0 in. lb.) Into new as-cast hole

7.1-8.6 N·m (61.8-74.8 in. lb.) Into used hole

Cam Gears

End Play .............................................................................................................. 0.5/1.5 mm (0.019/0.059 in.)

Running Side Clearance .................................................................................... 0.02/0.13 mm (0.001/0.005 in.)

Cam Gear-to-Cam Sha Running Assembly ................................................. 0.02/0.10 mm (0.001/0.004 in.)

Carburetor

Fuel Bowl Retaining Screw Torque ................................................................. 5.1-6.2 N·m (45-55 in. lb.)

Values are in metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil prior

to assembly, EXCEPT for air cleaner base thread forming screw - install dry.

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Section 1 Safety and General Information

Closure Plate

Closure Plate Fastener Torque ........................................................................ 24.5 N·m (216 in. lb.)

Balance Weight Guide Channel Width

New .............................................................................................................. 17.95/18.05 mm (0.707/0.711 in.)

Max. Wear Limit ......................................................................................... 18.13 mm (0.714 in.)

Connecting Rod

Cap Fastener Torque (torque in 2 increments).............................................. 5.5, 11.5 N·m (50, 100 in. lb.)

Connecting Rod-to-Crankpin Running Clearance

New ............................................................................................................... 0.03/0.055 mm (0.0012/0.0022 in.)

Max. Wear Limit .......................................................................................... 0.07 mm (0.0025 in.)

Connecting Rod-to-Crankpin Side Clearance ................................................ 0.25/0.59 mm (0.0098/0.0232 in.)

Connecting Rod-to-Piston Pin Running Clearance ....................................... 0.015/0.028 mm (0.0006/0.0011 in.)

Piston Pin End I.D.

New ............................................................................................................... 22.015/22.023 mm (0.8667/0.8670 in.)

Max. Wear Limit .......................................................................................... 22.036 mm (0.8675 in.)

Crankcase

Governor Cross Sha Bore I.D.

New ............................................................................................................... 6.025/6.05 mm (0.2372/0.2382 in.)

Max. Wear Limit .......................................................................................... 6.063 mm (0.2387 in.)

Oil Drain Plug Torque ....................................................................................... 14.0 N·m (125 in. lb.)

Crankshaft

End Play (free) .................................................................................................... 0.225/1.025 mm (0.0089/0.040 in.)

Cranksha Bore in Crankcase I.D.

New .............................................................................................................. 41.965/41.990 mm (1.6521/1.6531 in.)

Max. Wear Limit ......................................................................................... 42.016 mm (1.654 in.)

Cranksha Bore in Closure Plate I.D.

New .............................................................................................................. 44.965/44.990 mm (1.7703/1.7713 in.)

Max. Wear Limit ......................................................................................... 45.016 mm (1.7723 in.)

Flywheel End Main Bearing Journal O.D.

New - Before Serial No. 3703200003 ....................................................... 44.913/44.935 mm (1.7682/1.7691 in.)

New - Aer Serial No. 3703200013 ......................................................... 44.870/44.895 mm (1.7665/1.7675 in.)

O.D. - Max. Wear Limit ............................................................................. 44.84 mm (1.765 in.)

Max. Taper .................................................................................................. 0.0220 mm (0.0009 in.)

Max. Out of Round .................................................................................... 0.025 mm (0.001 in.)

PTO End Main Bearing Journal O.D.

New - Before Serial No. 3703200003 ........................................................ 41.913/41.935 mm (1.6501/1.6510 in.)

New - Aer Serial No. 3703200013 .......................................................... 41.855/41.880 mm (1.6478/1.6488 in.)

O.D. - Max. Wear Limit ............................................................................. 41.83 mm (1.647 in.)

Max. Taper .................................................................................................. 0.020 mm (0.0008 in.)

Max. Out of Round .................................................................................... 0.025 mm (0.001 in.)

1.8

Page 13

Section 1

Safety and General Information

Crankshaft (Continued)

Cranksha Bore in Closure Plate Running Clearance

New - Before Serial No. 3703200003 ........................................................ 0.030/0.077 mm (0.0012/0.0030 in.)

New - Aer Serial No. 3703200013 .......................................................... 0.070/0.120 mm (0.0027/0.0047 in.)

Cranksha Bore in Crankcase Running Clearance

New - Before Serial No. 3703200003 ........................................................ 0.030/0.077 mm (0.0012/0.0030 in.)

New - Aer Serial No. 3703200013 .......................................................... 0.085/0.135 mm (0.0033/0.0053 in.)

Connecting Rod Journal O.D.

New .............................................................................................................. 40.982/41.000 mm (1.6134/1.6141 in.)

Max. Wear Limit ......................................................................................... 40.964 mm (1.612 in.)

Max. Taper .................................................................................................. 0.012 mm (0.0005 in.)

Max. Out of Round .................................................................................... 0.025 mm (0.001 in.)

Cranksha T.I.R.

PTO End, Cranksha in Engine ............................................................... 0.15 mm (0.0059 in.)

Entire Cranksha, in V-Blocks ................................................................. 0.10 mm (0.0039 in.)

Cranksha Eccentrics O.D.

New .............................................................................................................. 66.940/66.970 mm (2.6354/2.6366 in.)

Max. Wear Limit ......................................................................................... 66.89 mm (2.633 in.)

Balance Weight

Balance Weight Bearing Surface I.D.

New .............................................................................................................. 67.011/67.086 mm (2.6382/2.6412 in.)

Max. Wear Limit ......................................................................................... 67.140 mm (2.6430 in.)

Balance Weight Pin O.D.

New .............................................................................................................. 11.950/11.975 mm (0.4705/0.4715 in.)

Max. Wear Limit ......................................................................................... 11.900 mm (0.4685 in.)

Guide Shoe Width - Before Serial No. 3618000003

New ............................................................................................................. 17.85/17.90 mm (0.703/0.705 in.)

Max. Wear Limit ......................................................................................... 17.75 mm (0.6988 in.)

Guide Shoe Hole I.D.

New .............................................................................................................. 12.000/12.025 mm (0.4724/0.4734 in.)

Max. Wear Limit ......................................................................................... 12.050 mm (0.4744 in.)

Linkage Pin O.D. (Crankcase) - Aer Serial No. 3618000013

New .............................................................................................................. 11.964/11.975 mm (0.4710/0.4715 in.)

Max. Wear Limit ......................................................................................... 11.900 mm (0.4685 in.)

Balance Weight Linkage- Aer Serial No. 3618000013

New .............................................................................................................. 11.985/12.010 mm (0.4719/0.4728 in.)

Max. Wear Limit ......................................................................................... 12.035 mm (0.4738 in.)

Balance Weight Screw Torque ......................................................................... 10.9-13.2 N·m (95.0-115.0 in. lb.)

1.9

Page 14

Section 1 Safety and General Information

Cylinder Bore

Cylinder Bore I.D. New

SV470, SV480-00XX .................................................................................. 84.000/84.025 mm (3.307/3.308 in.)

SV470, SV480-01XX .................................................................................. 89.000/89.025 mm (3.504/3.505 in.)

SV530, SV540 ............................................................................................. 89.000/89.025 mm (3.504/3.505 in.)

SV590, SV600, SV610, SV620 ................................................................... 94.010/94.035 mm (3.701/3.702 in.)

Max. Wear Limit

SV470, SV480-00XX .................................................................................. 84.073 mm (3.310 in.)

SV470, SV480-01XX .................................................................................. 84.073 mm (3.310 in.)

SV530, SV540 ............................................................................................. 89.073 mm (3.507 in.)

SV590, SV600, SV610, SV620 ................................................................... 94.073 mm (3.704 in.)

Max. Taper .................................................................................................. 0.05 mm (0.002 in.)

Max. Out of Round .................................................................................... 0.12 mm (0.0047 in.)

Cylinder Head

Cylinder Head Fastener Torque (torque in 2 increments) .......................... 20.5, 41.0 N·m (180, 360 in. lb.)

Max. Out-of-Flatness ........................................................................................ 0.8 mm (0.003 in.)

Rocker Arm Pivot Stud Torque ....................................................................... 13.5 N·m (120 in. lb.)

Rocker Arm Adjustment Nut Set Screw ........................................................ 5.5 N·m (50 in. lb.)

Electric Starter

Thru Bolt Torque ............................................................................................... 3.3-3.9 N·m (30-35 in. lb.)

Mounting Nut Torque ...................................................................................... 3.6 N·m (32 in. lb.)

Nut (Top) Positive (+) Brush Lead Terminal ................................................. 1.6-2.8 N·m (15-25 in. lb.)

Nut (Flange) Positive (+) Brush Lead Terminal ............................................ 2.2-4.5 N·m (20-40 in. lb.)

Fan/Flywheel

Flywheel Retaining Screw Torque M12 ......................................................... 88.0 N·m (65 . lb.)

Flywheel Retaining Screw Torque M10 ......................................................... 66.5 N·m (49 . lb.)

Governor

Governor Cross Sha-to-Crankcase Running Clearance ........................... 0.013/0.075 mm (0.0005/0.003 in.)

Governor Cross Sha O.D.

New .............................................................................................................. 5.975/6.012 mm (0.2352/0.2367 in.)

Max. Wear Limit ......................................................................................... 5.962 mm (0.2347 in.)

Governor Gear Sha-to-Governor Gear Running Clearance ..................... 0.09/0.16 mm (0.0035/0.0063 in.)

Governor Gear Sha O.D.

New ............................................................................................................. 5.99/6.00 mm (0.2358/0.2362 in.)

Max. Wear Limit ........................................................................................ 5.977 mm (0.02353 in.)

Ignition

Spark Plug Type (Champion® or Equivalent) ............................................... RC12YC or QC12YC

Spark Plug Gap .................................................................................................. 0.76 mm (0.030 in.)

1.10

Page 15

Section 1

Safety and General Information

Ignition (Continued)

Spark Plug Torque............................................................................................. 24-30 N·m (18-22 . lb.)

Ignition Module Air Gap ................................................................................ 0.203/0.305 mm (0.008/0.012 in.)

Ignition Module Fastener Torque ................................................................... 6.0 N·m (55 in. lb.) Into new as-cast hole

4.0 N·m (35 in. lb.) Into used hole

Muﬄer

Muﬄer Retaining Nuts Torque ...................................................................... 24.4 N·m (216 in. lb.)

Oil Filter

Oil Filter Torque ................................................................................................ refer to the oil ﬁlter for instructions.

Oil Filter Pad Pipe Plug

1/8” N.P.T.F. Torque .......................................................................................... 4.5-5.0 N·m (40-46 in. lb.)

Oil Pump

Mounting Screw Torque .............................................................5.0-7.5 N·m (44.4-66.0 in. lb.) Into new as-cast hole

3.8-4.6 N·m (33.3-40.3 in. lb.) Into used hole

Pump Gears-to-Crankcase Side Clearance .................................................... 0.165/0.315 mm (0.0065/0.0124 in.)

Oil Sentry

Pressure Switch Torque .................................................................................... 4.5-5.0 N·m (40-45 in. lb.)

Piston, Piston Rings, and Piston Pin

Piston Pin Bore I.D.

New .............................................................................................................. 22.006/22.012 mm (0.8685/0.8666 in.)

Max. Wear Limit ......................................................................................... 22.025 mm (0.8671 in.)

Piston Pin O.D.

New .............................................................................................................. 21.995/22.0 mm (0.8659/0.8661 in.)

Max. Wear Limit ......................................................................................... 21.994 mm (0.8658 in.)

Top Compression Ring-to-Groove Side Clearance ..................................... 0.04 mm (0.0016 in.)

Middle Compression Ring-to-Groove Side Clearance ............................... 0.04 mm (0.0016 in.)

Top and Middle Compression Ring End Gap New Bore

Top Ring .................................................................................................... 0.15/0.40 mm (0.006/0.016 in.)

Middle Ring .............................................................................................. 0.30/0.55 mm (0.012/0.022 in.)

Used Bore (max.) ........................................................................................ 0.77 mm (0.030 in.)

Piston Thrust Face O.D.² SV470, SV480-00XX

New ............................................................................................................ 83.948/83.962 mm (3.3050/3.3056 in.)

Max. Wear Limit ....................................................................................... 83.828 mm (3.3003 in.)

SV470, SV480-01XX

New ............................................................................................................ 88.948/88.962 mm (3.5018/3.5024 in.)

Max. Wear Limit ....................................................................................... 88.828 mm (3.4972 in.)

²Measure 8 mm (0.314 in.) above the boom of the piston skirt at right angles to the piston pin.

1.11

Page 16

Section 1 Safety and General Information

Piston, Piston Rings, and Piston Pin (Continued)

SV530, SV540

New ............................................................................................................ 88.948/88.962 mm (3.5018/3.5024 in.)

Max. Wear Limit ....................................................................................... 88.828 mm (3.4972 in.)

SV590, SV600, SV610, SV620

New ............................................................................................................ 93.928/93.942 mm (3.6980/3.6985 in.)

Max. Wear Limit ....................................................................................... 93.828 mm (3.6940 in.)

Piston Thrust Face-to-Cylinder Bore

SV470, SV480, SV530, SV540 .................................................................... 0.045 mm (0.0018 in.)

SV560, SV590, SV600, SV610, SV620 ....................................................... 0.0880 mm (0.0035 in.)

Rectiﬁer-Regulator

Mounting Screw Torque ................................................................................... 6.0 N·m (55 in. lb.) Into new as cast hole

4.0 N·m (35 in. lb.) Into used hole

Speed Control

Speed Control Bracket Assembly Fastener Torque ......................................11.0 N·m (95 in. lb.) Into new as-cast hole

7.5 N·m (65 in. lb.) Into used hole

Stator

Stator Mounting Screw Torque ....................................................................... 6.0 N·m (55 in. lb.) Into new as-cast hole

4.0 N·m (35 in. lb.) Into used hole

Throttle/Choke Controls

Governor Control Lever Fastener Torque ..................................................... 7.0-8.5 N·m (60-75 in. lb.)

Running Clearance

Valve Cover

Valve Cover Fastener Torque........................................................................... 11.0 N·m (95 in. lb.) Into new as-cast hole

7.5 N·m (65 in. lb.) Into used hole

Valves and Valve Lifters

Intake Valve Lash3 ............................................................................................. 0.127 mm (0.005 in.)

Exhaust Valve Lash3 .......................................................................................... 0.178 mm (0.007 in.)

Intake Valve Minimum Li ............................................................................. 8.9 mm (0.350 in.)

Exhaust Valve Minimum Li .......................................................................... 8.9 mm (0.350 in.)

Nominal Valve Seat Angle ............................................................................... 45°

Intake Valve Stem-to-Valve Guide Running Clearance ............................... 0.038/0.076 mm (0.0015/0.003 in.)

Exhaust Valve Stem-to-Valve Guide Running Clearance ............................ 0.050/0.88 mm (0.0020/0.0035 in.)

Intake Valve Guide I.D.

New .............................................................................................................. 6.038/6.058 mm (0.2377/0.2385 in.)

Max. Wear Limit ......................................................................................... 6.135 mm (0.2415 in.)

Measure 8 mm (0.314 in.) above the boom of the piston skirt at right angles to the piston pin.

Check valve lash every 200 hours, adjust as required.

1.12

Page 17

Section 1

Safety and General Information

Valves and Valve Lifters (Continued)

Intake Valve Stem Diameter

New .............................................................................................................. 5.982/6.0 mm (0.2355/0.2362 in.)

Exhaust Valve Guide I.D.

New .............................................................................................................. 6.038/6.058 mm (0.2377/0.2385 in.)

Max. Wear Limit ......................................................................................... 6.160 mm (0.2425 in.)

Exhaust Valve Stem Diameter

New .............................................................................................................. 5.970/5.988 mm (0.235/0.2357 in.)

General Torque Values

Metric Fastener Torque Recommendations for Standard Applications

Tightening Torque: N·m (in. lb.) + or - 10%

Property Class

Noncritical

4.8

Size M4 1.2 (11) 1.7 (15) 2.9 (26) 4.1 (36) 5.0 (44) 2.0 (18) M5 2.5 (22) 3.2 (28) 5.8 (51) 8.1 (72) 9.7 (86) 4.0 (35) M6 4.3 (38) 5.7 (50) 9.9 (88) 14.0 (124) 16.5 (146) 6.8 (60) M8 10.5 (93) 13.6 (120) 24.4 (216) 33.9 (300) 40.7 (360) 17.0 (150)

5.8 8.8 10.9 12.9

Fasteners

Into Aluminum

Tightening Torque: N·m (ft. lb.) + or - 10%

Property Class

4.8

M10 21.7 (16) 27.1 (20) 47.5 (35) 66.4 (49) 81.4 (60) 33.9 (25) M12 36.6 (27) 47.5 (35) 82.7 (61) 116.6 (86) 139.7 (103) 61.0 (45) M14 58.3 (43) 76.4 (55) 131.5 (97) 184.4 (136) 219.7 (162) 94.9 (70)

5.8 8.8 10.9 12.9

Oil Drain Plugs Tightening Torque: N•m (English)

Size 1/8" NPT 1/4" 3/8" 1/2" 3/4" X-708-1

Into Cast Iron

–

17.0 (150 in. lb.)

20.3 (180 in. lb.)

27.1 (20 . lb.)

33.9 (25 . lb.)

27.1/33.9 (20/25 . lb.)

Into Aluminum

4.5 (40 in. lb.)

11.3 (100 in. lb.)

13.6 (120 in. lb.)

17.6 (13 . lb.)

21.7 (16 . lb.)

27.1/33.9 (20/25 . lb.)

Conversions

N·m = in. lb. x 0.113 N·m = . lb. x 1.356 in. lb. = N·m x 8.85 . lb. = N·m x 0.737

Noncritical

Fasteners

Into Aluminum

Torque

1.13

Page 18

Section 1 Safety and General Information

1.14

Page 19

Section 2

Tools & Aids

Section 2

Tools & Aids

Certain quality tools are designed to help you perform speciﬁc disassembly, repair, and reassembly procedures. By using tools designed for the job, you can properly service engines easier, faster, and safer! In addition, you’ll increase your service capabilities and customer satisfaction by decreasing engine downtime.

Here is the list of tools and their source.

Separate Tool Suppliers:

Kohler Tools Contact your source

of supply.

SE Tools

415 Howard St. Lapeer, MI 48446 Phone 810-664-2981 Toll Free 800-664-2981 Fax 810-664-8181

Design Technology Inc. 768 Burr Oak Drive Westmont, IL 60559 Phone 630-920-1300

Tools

Description Source/Part No.

Balance Gear Timing Tool (K & M Series)

To hold balance gears in timed position when assembling engine.

Camsha Endplay Plate

For checking camsha endplay.

Camsha Seal Protector (Aegis)

To protect seal during camsha installation.

Cylinder Leakdown Tester

For checking combustion retention and if cylinder, piston, rings, or valves are worn.

Electronic Fuel Injection (EFI) Diagnostic Soware

Use with Laptop or Desktop PC.

EFI Service Kit

For troubleshooting and seing up an EFI engine.

Individual Components Available

Pressure Tester Noid Light

90° Adapter Oetiker Clamp Pliers Code Plug, Red Wire Code Plug, Blue Wire

Flywheel Holding Tool (CS Series) SE Tools KLR-82407

Flywheel Puller

To remove ﬂywheel from engine.

Flywheel Strap Wrench

To hold ﬂywheel during removal.

Kohler 25 455 06-S

(Formerly Y-357)

SE Tools KLR-82405

SE Tools KLR-82417

Kohler 25 761 05-S

Kohler 25 761 23-S

Kohler 24 761 01-S

Design Technology Inc.

DTI-019 DTI-021 DTI-023 DTI-025 DTI-027 DTI-029

SE Tools KLR-82408

SE Tools KLR-82409

2.1

Page 20

Section 2 Tools & Aids

Tools (Continued)

Description Source/Part No.

Hydraulic Valve Lier Tool

To remove and install hydraulic liers.

Ignition System Tester

For testing output on all systems, except CD. For testing output on capacitive discharge (CD) ignition system.

Oﬀset Wrench (K & M Series)

To remove and reinstall cylinder barrel retaining nuts.

Oil Pressure Test Kit

To test and verify oil pressure.

Rectiﬁer-Regulator Tester (120 volt current) Rectiﬁer-Regulator Tester (240 volt current)

Used to test rectiﬁer-regulators.

Kohler 25 761 38-S

Kohler 25 455 01-S Kohler 24 455 02-S

SE Tools KLR-82410

Kohler 25 761 06-S

Kohler 25 761 20-S Kohler 25 761 41-S

Individual Components Available CS-PRO Regulator Test Harness Special Regulator Test Harness with Diode

Spark Advance Module (SAM) Tester

To test the SAM (ASAM and DSAM) on engines with SMART-SPARK™.

Starter Retaining Ring Tool (Inertia Drive)

To remove and reinstall drive retaining rings (excluding FASCO starters).

Starter Servicing Kit (All Starters)

To remove and reinstall drive retaining rings and brushes. Individual Component Available

Starter Brush Holding Tool (Solenoid Shift)

Tachometer (Digital Inductive)

For checking operating speed (RPM) of an engine.

Vacuum/Pressure Tester

Alternative to a water manometer.

Valve Guide Reamer (K & M Series)

For sizing valve guides after installation.

Design Technology Inc.

DTI-031 DTI-033

Kohler 25 761 40-S

Kohler 25 761 18-S

SE T ools KLR-8241 1

SE T ools KLR-82416

Design T echnology Inc.

DTI-110

Kohler 25 761 22-S

SE T ools KLR-1 1843

2.2

Page 21

Section 2

Tools & Aids

Aids

Description Source/Part No.

Camsha Lubricant (Valspar ZZ613) Kohler 25 357 14-S

Dielectric Grease (GE/Novaguard G661) Kohler 25 357 11-S

Dielectric Grease (Fel-Pro) Lubri-Sel

Electric Starter Drive Lubricant (Inertia Drive) Kohler 52 357 01-S

Electric Starter Drive Lubricant (Solenoid Shi) Kohler 52 357 02-S

RTV Silicone Sealant

Loctite® 5900 Heavy Body in 4 oz aerosol dispenser. Only oxime-based, oil resistant RTV sealants, such as those listed, are approved for use. Loctite® Nos. 5900 or 5910 are recommended for best sealing characteristics. Loctite® 5910 Loctite® Ultra Black 598 Loctite® Ultra Blue 587

Loctite® Ultra Copper

Spline Drive Lubricant Kohler 25 357 12-S

Kohler 25 597 07-S

2.3

Page 22

Section 2 Tools & Aids

Special Tools You Can Make

Flywheel Holding Tool

A ﬂywheel holding tool can be made out of an old junk ﬂywheel ring gear as shown in Figure 2-1, and used in place of a strap wrench.

1. Using an abrasive cut-oﬀ wheel, cut out a six

tooth segment of the ring gear as shown.

2. Grind oﬀ any burrs or sharp edges.

3. Invert the segment and place it between the ignition bosses on the crankcase so that the tool teeth engage the ﬂywheel ring gear teeth. The bosses will lock the tool and ﬂywheel in position for loosening, tightening or removing with a puller.

2. Remove the studs of a Posi-Lock rod or grind oﬀ the aligning steps of a Command rod, so the joint surface is ﬂat.

3. Find a 1 in. long capscrew with the correct thread size to match the threads in the connecting rod.

4. Use a ﬂat washer with the correct I.D. to slip on the capscrew and approximately 1” O.D. (Kohler Part No. 12 468 05-S). Assemble the capscrew and washer to the joint surface of the rod, as shown in Figure 2-2.

Figure 2-1. Flywheel Holding Tool.

Rocker Arm/Crankshaft Tool

A spanner wrench to li the rocker arms or turn the cranksha may be made out of an old junk connecting rod.

1. Find a used connecting rod from a 10 HP or larger engine. Remove and discard the rod cap.

Figure 2-2. Rocker Arm/Crankshaft Tool.

2.4

Page 23

Section 3

Troubleshooting

Troubleshooting Guide

When troubles occur, be sure to check the simple

causes which, at ﬁrst, may seem too obvious to be

considered. For example, a starting problem could be

caused by an empty fuel tank.

Some common types of engine troubles are listed

below. Use these to help locate the possible cause(s).

Engine Cranks But Will Not Start

1. Empty fuel tank.

2. Fuel shut-oﬀ valve closed.

3. Poor fuel, dirt or water in the fuel system.

4. Clogged fuel line.

5. Spark plug lead disconnected.

6. Kill switch in oﬀ position.

7. Faulty spark plug.

8. Faulty ignition module.

9. Fuel solenoid malfunction.

10. Choke not closing.

11. Baery connected backwards.

12. Safety interlock system engaged.

Engine Starts But Does Not Keep Running

1. Restricted fuel tank cap vent.

2. Poor fuel, dirt or water in the fuel system.

3. Faulty or misadjusted choke or throle controls.

4. Loose wires or connections that short the kill

terminal of ignition module to ground.

5. Faulty cylinder head gasket.

6. Faulty carburetor.

7. Intake system leak.

Engine Starts Hard

1. PTO drive is engaged.

2. Poor fuel, dirt or water in the fuel system.

3. Clogged fuel line.

4. Loose or faulty wires or connections.

5. Faulty or misadjusted choke or throle controls.

6. Faulty spark plug.

7. Low compression.

8. Faulty ACR mechanism.

9. Weak spark.

10. Fuel pump malfunction causing lack of fuel.

Section 3

Troubleshooting

11. Engine overheated-cooling/air circulation

restricted.

12. Flywheel key sheared.

13. Intake system leak.

Engine Will Not Crank

1. PTO drive is engaged.

2. Baery is discharged.

3. Safety interlock switch is engaged.

4. Loose or faulty wires or connections.

5. Faulty key switch or ignition switch.

6. Faulty electric starter.

7. Seized internal engine components.

Engine Runs But Misses

1. Dirt or water in the fuel system.

2. Spark plug faulty or fouled.

3. Poor quality of fuel.

4. Spark plug lead boot loose on plug.

5. Loose wires or connections that intermiently short the kill terminal of ignition module to

ground.

6. Engine overheated.

7. Faulty ignition module or improperly gapped.

8. Carburetor adjusted incorrectly.

Engine Will Not Idle

1. Dirt or water in the fuel system.

2. Stale fuel and/or gum in carburetor.

3. Faulty spark plug.

4. Fuel supply inadequate.

5. Idle fuel adjusting needle improperly set.

6. Idle speed adjusting screw improperly set.

7. Low compression.

8. Restricted fuel tank cap vent.

9. Engine overheated-cooling system/air circulation

problem.

3.1

Page 24

Section 3 Troubleshooting

Engine Overheats

1. Air intake/grass screen, cooling ﬁns, or cooling

shrouds clogged.

2. Excessive engine load.

3. Low crankcase oil level.

4. High crankcase oil level.

5. Faulty carburetor.

6. Lean fuel mixture.

Engine Knocks

1. Excessive engine load.

2. Low crankcase oil level.

3. Old or improper fuel.

4. Internal wear or damage.

5. Quality of fuel.

6. Incorrect grade of oil.

Engine Loses Power

1. Low crankcase oil level.

2. High crankcase oil level.

3. Dirty air cleaner element.

4. Dirt or water in the fuel system.

5. Excessive engine load.

6. Engine overheated.

7. Faulty spark plug.

8. Low compression.

9. Exhaust restriction.

10. Low baery.

11. Incorrect governor seing.

Engine Uses Excessive Amount of Oil

1. Incorrect oil viscosity/type.

2. Clogged, broken, or inoperative breather.

3. Worn or broken piston rings.

4. Worn cylinder bore.

5. Worn valve stems/valve guides.

6. Crankcase overﬁlled.

7. Blown head gasket/overheated.

• Check for buildup of dirt and debris on the crankcase, cooling ﬁns, grass screen and other external surfaces. Dirt or debris on these areas can cause overheating.

• Check for obvious oil leaks and damaged components. Excessive oil leakage can indicate a clogged or inoperative breather, worn or damaged seals or gaskets, or loose fasteners.

• Check the air cleaner cover and base for damage or indications of improper ﬁt and seal.

• Check the air cleaner element. Look for holes, tears, cracked or damaged sealing surfaces, or other damage that could allow unﬁltered air into the engine. Also note if the element is dirty or clogged. These could indicate improper

maintenance.

• Check the carburetor throat for dirt. Dirt in the throat is further indication that the air cleaner was not functioning properly.

• Check if the oil level is within the operating range on the dipstick. If it is above, sniﬀ for gasoline

odor.

• Check the condition of the oil. Drain the oil into a container; it should ﬂow freely. Check for metal chips and other foreign particles.

Sludge is a natural by-product of combustion; a small accumulation is normal. Excessive sludge formation could indicate the wrong type or weight of oil was

used, the oil was not changed at the recommended

intervals, an over-rich fuel mixture, or weak ignition, to name a few possible causes.

Oil Leaks from Oil Seals, Gaskets

1. Clogged, broken, or inoperative breather.

2. Worn or broken piston rings.

3. Piston blowby, or leaky valves.

4. Restricted exhaust.

External Engine Inspection

Before cleaning or disassembling the engine, make a thorough inspection of its external appearance and condition. This inspection can give clues to what might be found inside the engine (and the cause)

when it is disassembled.

3.2

NOTE: It is good practice to drain oil at a location

away from the workbench. Be sure to allow ample time for complete drainage.

Cleaning the Engine

Aer inspecting the external condition of the engine, clean the engine thoroughly before disassembling it. Also clean individual components as the engine is disassembled. Only clean parts can be accurately inspected and gauged for wear or damage. There are many commercially available cleaners that will quickly remove grease, oil, and grime from

engine parts. When such a cleaner is used, follow the manufacturer’s instructions and safety precautions carefully.

Page 25

Section 3

Troubleshooting

Make sure all traces of the cleaner are removed before

the engine is reassembled and placed into operation.

Even small amounts of these cleaners can quickly break down the lubricating properties of engine oil.

Basic Engine Tests

Crankcase Vacuum Test

A partial vacuum should be present in the

crankcase when the engine is operating. Pressure

in the crankcase (normally caused by a clogged or improperly-operating breather) can cause oil to be forced out at oil seals, gaskets, or other available spots.

Crankcase vacuum is best measured with a water manometer or vacuum/pressure test gauge. See Section 2. Complete instructions are provided with the

testers.

Test the crankcase vacuum with the manometer as follows:

1. Insert the rubber stopper into the oil ﬁll hole.

Be sure the pinch clamp is installed on the hose and use the tapered adapters to connect

the hose between the stopper and one of the manometer tubes. Leave the other tube open to the atmosphere. Check that the water level in the

manometer is at the “0” line. Make sure the pinch clamp is closed.

2. Start the engine and run at no-load high idle speed (3200 to 3750 RPM).

3. Open the clamp and note the water level in the

tube.

The level in the engine side should be a minimum

of 10.2 cm (4 in.) above the level in the open side.

If the level in the engine side is the same as the

open side (no vacuum), or the level in the engine side is lower than the level in the open side (pressure), check for the conditions in the table

below.

4. Close the pinch clamp before stopping the engine.

To perform the test with the vacuum/pressure gauge:

1. Insert the stopper as in step 1.

2. Insert the barbed gauge ﬁing into the hole in the

stopper. Be sure the gauge needle is at “0”.

3. Run the engine, as in step 2, and observe the gauge reading. Needle movement to the le of “0” is a vacuum, and movement to the right indicates a pressure. A minimum of 10.2 cm (4 in.) of vacuum should be present.

Incorrect Vacuum in Crankcase

Possible Cause Solution

1. Crankcase breather clogged or inoperative.

2. Seals and/or gaskets leaking. Loose or improperly torqued fasteners.

3. Piston blowby or leaky valves. Conﬁrm with cylinder leakdown test.

4. Restricted exhaust.

1. Disassemble breather, clean parts thoroughly,

reassemble, and recheck pressure.

2. Replace all worn or damaged seals and gaskets.

Make sure all fasteners are tightened securely. Use appropriate torque values and sequences when necessary.

3. Recondition piston, rings, cylinder bore, valves, and valve guides.

4. Repair/replace restricted muﬄer/exhaust system.

3.3

Page 26

Section 3 Troubleshooting

Compression Test

These engines are equipped with an automatic

compression release (ACR) mechanism. Because of the ACR mechanism, it is diﬃcult to obtain an accurate compression reading. As an alternate, use the

leakdown test described below.

Cylinder Leakdown Test

A cylinder leakdown test can be a valuable alternative to a compression test. By pressurizing the combustion chamber from an external air source, you can determine if the valves or rings are leaking, and how badly.

The cylinder leakdown tester is a relatively simple, inexpensive leakdown tester for small engines. The tester includes a quick disconnect coupling for aaching the adapter hose and a holding tool.

Leakdown Test Instructions

1. Run the engine for 3-5 minutes to warm it up.

2. Remove the spark plug.

3. Rotate the cranksha until the piston is at top dead center of the compression stroke. You

will need to hold the engine in this position while testing. The holding tool supplied with

the tester can be used if the PTO end of the cranksha is accessible. Slide the holding tool onto the cranksha, align the slot with one of the mounting holes on the PTO face, and tighten it onto the cranksha. Install a 3/8" breaker bar into

the slot of the holding tool, so it is perpendicular to both the holding tool and cranksha, or insert

a shoulder bolt through the slot and thread it into

the mounting hole. If the ﬂywheel end is more accessible, you can use a breaker bar and socket on the ﬂywheel nut/screw to hold it in position. You may need an assistant to hold the breaker bar during testing. If the engine is mounted in a piece of equipment, you may be able to hold it by clamping or wedging a driven component. Just be certain that the engine cannot rotate oﬀ of

TDC in either direction.

4. Install the adapter into the spark plug hole, but

do not aach it to the tester at this time.

5. Connect an adequate air source (80-100 psi) to the tester.

6. Turn the regulator knob in the increase (clockwise) direction until the gauge needle is in

the yellow set area at the low (right) end of the

scale.

7. Connect the tester quick-disconnect to the

adapter. Note the gauge reading and listen for

escaping air at the carburetor inlet, exhaust

outlet, and/or crankcase breather.

8. Check your test results against the table below:

Leakdown Test Results

Air escaping from crankcase breather ................................................Defective rings or worn cylinder walls.

Air escaping from exhaust system ......................................................Defective exhaust valve.

Air escaping from carburetor ...............................................................Defective intake valve.

Gauge reading in low (green) zone .....................................................Piston rings and cylinder in good condition.

Gauge reading in moderate (yellow) zone .........................................Engine is still usable, but there is some wear

present. Customer should start planning for overhaul or replacement.

Gauge reading in high (red) zone ........................................................Rings and/or cylinder have considerable wear.

Engine should be reconditioned or replaced.

3.4

Page 27

Air Cleaner and Air Intake System

Section 4

Air Cleaner and Air Intake System

Section 4

Air Cleaner

These engines are equipped with a replaceable, high density, paper air cleaner element. Some engines also have an oiled, foam precleaner, located in the outer air cleaner cover. See Figure 4-1.

Air Cleaner Base

Optional Foam Precleaner

Intake air is drawn in through the upper opening from the blower housing, passes through the precleaner (if so equipped), the paper element and then into the carburetor. The outer air cleaner cover is secured by two knobs, and removed by turning the knobs counterclockwise.

Air Cleaner Element

Air Cleaner Cover

Figure 4-1. Air Cleaner Assembly - Exploded View.

Check the air cleaner daily or before starting the engine. Check for and correct any buildup of dirt and

debris, and loose or damaged components.

NOTE: Operating the engine with loose or

damaged air cleaner components could allow unﬁltered air into the engine causing premature wear and failure.

Air Cleaner Cover Knobs

Precleaner Service

If so equipped, wash and oil the precleaner annually or every 25 hours of operation (more oen under extremely dusty or dirty conditions).

1. Loosen the air cleaner cover knobs and remove the cover.

2. Remove the precleaner.

4.1

Page 28

Section 4 Air Cleaner and Air Intake System

3. Wash the precleaner in warm water with detergent. Rinse the precleaner thoroughly until all traces of detergent are eliminated. Squeeze out excess water (do not wring). Allow the precleaner to air dry.

4. Saturate the precleaner with new engine oil. Squeeze out all excess oil.

5. Reinstall the precleaner into the outer cover.

6. Install the air cleaner cover and secure with the two knobs.

7. When precleaner replacement is necessary, order Kohler Part No. 20 083 03-S.

Paper Element Service

Check the paper element annually or every 25 hours of operation (more oen under extremely dusty or dirty conditions). Clean or replace the element as necessary. Replace the air cleaner element annually or every 100 hours.

1. Remove the air cleaner cover and the precleaner (if so equipped), service as required.

2. Remove the air cleaner element with the integral rubber seal.

8. When element replacement is necessary, order

Kohler Part No. 20 083 02-S.

Inspect Air Cleaner Components

Whenever the air cleaner cover is removed, or the paper element or precleaner is serviced, check the following areas/components:

Outer Air Cleaner Cover - Make sure the air cleaner cover is in good condition, not cracked, damaged, or missing a retaining knob, which can aﬀect the sealing ability of the air cleaner element.

Air Cleaner Base - Make sure the base is properly secured and not cracked or damaged. Since the air cleaner base and carburetor are secured to the intake port with common hardware, it is extremely important that the fasteners securing these components are tight at all times. The air cleaner base also provides the mounting points for the air cleaner cover retaining studs. Make sure the bosses are not cracked, broken or damaged, and the studs are properly secured.

Before reinstalling an air cleaner base that has been removed, make sure the metal bushings in the base mounting holes are present. See Figure 4-2. The bushings prevent damage to the base and maintain the proper mounting torque.

3. Gently tap the pleated side of the paper element to dislodge dirt. Do not wash the paper element or use pressurized air, as this will damage the element. Replace a dirty, bent, or damaged element with a genuine Kohler element. Handle new elements carefully; do not use if the rubber seal is damaged.

4. Clean all air cleaner components of any accumulated dirt or foreign material. Prevent any dirt from entering the throat of the carburetor.

5. Install the air cleaner element with the pleated side out and seat the rubber seal onto the edges of the air cleaner base.

6. Reinstall the precleaner (if so equipped), into the upper section of the air cleaner cover. Make sure the hole in the precleaner is aligned with the upper mounting knob. See Figure 4-1.

7. Reinstall the air cleaner cover and secure with the two knobs.

Figure 4-2. Bushings in Air Cleaner Base.

Breather Hose - Make sure the hose is not cracked or damaged, and aached to both the air cleaner base and valve cover.

NOTE: Damaged, worn, or loose air cleaner

components can allow unﬁltered air into the engine causing premature wear and failure. Tighten or replace all loose or damaged components.

4.2

Page 29

Figure 4-3. Breather Hose.

Disassembly

The following procedure is for complete disassembly of all air cleaner components. As the removal of the air cleaner base also aﬀects carburetor mounting and governor adjustment, steps 3 and 4 should only be performed if required. Detailed photos are provided in Sections 5, 8, and 10 for the various individual steps.

Section 4

Air Cleaner and Air Intake System

Reassembly

The following procedure is for complete assembly of all air cleaner components. Steps 1-3 are necessary only if the air cleaner base and/or the cover mounting studs were removed in Section 8, Disassembly.

1. Install the mounting studs into the air cleaner base if removed previously. Tighten the studs until boomed, or to the end of threads (do not force).

2. Install the air cleaner base gasket and air cleaner base, with the two metal spacers, onto the mounting stud(s) and/or alignment pin. Make sure the upper mounting tab is located above the closure plate. Install and ﬁnger tighten the hex ﬂange nut(s). When a long M6 thread forming mounting screw is used, apply hand pressure to keep the parts from shiing, then remove the alignment pin and install the M6 thread forming screw. DO NOT OIL. Torque the nut(s) to

5.5 N·m (48 in. lb.). Torque the screw to 8.0 N·m

(70 in. lb.) into a new hole, or 5.5 N·m (48 in. lb.)

into a used hole, do not over tighten.

1. Loosen the air cleaner cover retaining knobs and remove the air cleaner cover.

2. Remove the foam precleaner (if so equipped), and the air cleaner element with formed rubber seal.

3. Disconnect the breather hose from the valve cover or air cleaner base.

NOTE: The air cleaner base should be removed

only if necessary.

4. Remove the two hex ﬂange nuts from the mounting studs. If one stud and one thread forming screw is used; ﬁrst remove the thread forming screw on the right side of the carburetor inlet, which secures the air cleaner base, carburetor and gaskets. Insert a 3/16” diameter rod approximately 4” long, into the hole to serve as a temporary alignment pin. Be careful not to force the rod or damage the threads. Then remove the hex ﬂange nut from the stud on the le side of the carburetor inlet. Carefully remove the air cleaner base and gasket. The cover mounting studs thread into the air cleaner base, and they should only be removed if necessary.

3. Reconnect the breather hose and perform the governor adjustment (Section 5, Initial Governor Adjustment).

4. Install the air cleaner element with the pleated side out and seat the rubber seal onto the edges of the air cleaner base.

5. Install the serviced precleaner (if so equipped) into the air cleaner cover. Make sure the hole in the precleaner is aligned with the upper mounting knob.

6. Reinstall the air cleaner cover and secure with the two knobs.

4.3

Page 30

Section 4 Air Cleaner and Air Intake System

Air Intake/Cooling System

Clean Air Intake/Cooling Areas

To ensure proper cooling, make sure the grass screen, cooling ﬁns, and other external surfaces of the engine are kept clean at all times.

Annually or every 100 hours of operation, (more oen under extremely dusty, dirty conditions), remove the blower housing and any other cooling shrouds. Clean the cooling ﬁns and external surfaces as necessary. Make sure all parts are reinstalled. Torque the M6 blower housing fasteners to 7.7 N·m (68.3 in. lb.).

NOTE: Operating the engine with a blocked grass

screen, dirty or plugged cooling ﬁns, and/or cooling shrouds removed, will cause engine damage due to overheating.

4.4

Page 31

Fuel System and Governor

Section 5

Fuel System and Governor

Section 5

Fuel Recommendations

WARNING: Explosive Fuel!

Gasoline is extremely ﬂammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well-ventilated, unoccupied buildings, away from sparks or ﬂames. Do not ﬁll the fuel tank while the engine is hot or running, since spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Do not start the engine near spilled fuel. Never use gasoline as a cleaning agent.

General Recommendations

Purchase gasoline in small quantities and store in clean, approved containers. A container with a capacity of 2 gallons or less with a pouring spout is recommended. Such a container is easier to handle and helps eliminate spillage during refueling.

• Do not use gasoline le over from the previous season, to minimize gum deposits in your fuel system and to ensure easy starting.

• Do not add oil to the gasoline.

• Do not overﬁll the fuel tank. Leave room for the fuel to expand.

Gasoline/Ether blends

Methyl Tertiary Butyl Ether (MTBE) and unleaded gasoline blends (up to a maximum of 15% MTBE by volume) are approved as a fuel for Kohler engines. Other gasoline/ether blends are not approved.

Fuel System

The typical fuel system and related components include the fuel tank, in-line fuel ﬁlter, fuel pump, carburetor, and fuel lines. Some applications use gravity feed without a fuel pump.

Operation

The fuel from the tank is moved through the in-line ﬁlter and fuel lines by the fuel pump. On engines not equipped with a fuel pump, the fuel tank outlet is located above the carburetor inlet and gravity moves the fuel.

Fuel then enters the carburetor ﬂoat bowl and is moved into the carburetor body. There, the fuel is mixed with air. This fuel-air mixture is then burned in the engine combustion chamber.

Troubleshooting

Use the following procedure to check if fuel is reaching the combustion chamber.

Fuel Type

For best results use only clean, fresh, unleaded gasoline with a pump sticker octane rating of 87 (R+M)/2 or higher. In countries using the Research Octane Number (RON), it should be 90 octane minimum. Leaded gasoline is not recommended and must not be used on EFI engines or on other models where exhaust emissions are regulated.

Gasoline/Alcohol blends

5.1

Page 32

Section 5 Fuel System and Governor

Fuel System Troubleshooting Guide

Test Conclusion

1. Check for the following: a. Make sure the fuel tank contains clean, fresh,

proper fuel. b. Make sure the vent in fuel cap is open. c. Make sure the fuel valve is open.

2. Check for fuel in the combustion chamber. a. Disconnect and ground spark plug lead. b. Close the choke on the carburetor. c. Crank the engine several times. d. Remove the spark plug and check for fuel at

the tip.

3. Check for fuel ﬂow from the tank to the fuel pump. a. Remove the fuel line from the inlet ﬁing of

the fuel pump. b. Hold the line below the boom of the tank.

Open the shutoﬀ valve (if so equipped) and

observe ﬂow.

4. Check the operation of fuel pump. a. Remove the fuel line from the inlet ﬁing of

the carburetor. b. Crank the engine several times and observe

ﬂow.

2. If there is fuel at the tip of the spark plug, fuel is

reaching the combustion chamber.

If there is no fuel at the tip of the spark plug, check

for fuel ﬂow from the fuel tank (Test 3).

3. If fuel does ﬂow from the line, reconnect line and

check for faulty fuel pump (Test 4).

If fuel does not ﬂow from the line, check for

clogged fuel tank vent, fuel pickup screen, shutoﬀ valve, and fuel lines.

4. If fuel does ﬂow from the line, check for faulty

carburetor. (Refer to the "Carburetor" portions of this section.)

If fuel does not ﬂow from the line, check for

clogged fuel line. If the fuel line is unobstructed, the fuel pump is faulty and must be replaced.

Fuel Filter

Some engines are equipped with an in-line fuel ﬁlter. Periodically inspect the ﬁlter and replace when dirty. Replacement is recommended annually or every 100 hours. Use a genuine Kohler ﬁlter.

Fuel Line

These engines use low permeation rated fuel lines, certiﬁed to comply with California and U.S. EPA evaporative emission requirements. Fuel lines that do not meet these requirements may not be used. Order replacement hose through a Kohler Service Center.

Fuel Pump

Some engines are equipped with an optional pulse fuel pump. See Figure 5-1.

Operation

The fuel pump has two internal chambers separated by a diaphragm. The air chamber is connected to the engine crankcase by a rubber hose. The fuel chamber has an inlet from the fuel tank, and an outlet to the carburetor. The inlet and outlet each have an internal, one-way check valve.

Alternating negative and positive pressures in the crankcase activate the pump. When the piston moves upward in the cylinder, negative pressure (vacuum) is created in the crankcase and in the air chamber of the pump. The diaphragm ﬂexes toward the negative pressure, and the suction draws fuel past the inlet check valve, into the fuel chamber. Downward movement of the piston causes a positive pressure in the crankcase and air chamber, pushing the diaphragm in the opposite direction, puing pressure on the fuel. The inlet check valve has now closed, so the fuel is forced past the outlet check valve, to the carburetor.

Repair

Pulse fuel pumps are not serviceable and must be replaced when faulty.

Removal

1. Disconnect the inlet, outlet, and pulse lines from the fuel pump. Mark the lines for proper reassembly.

2. Remove the hex ﬂange screws aaching the fuel pump.

5.2

Page 33

Installation

1. Install the new fuel pump, and secure with the hex ﬂange screws. Torque the hex ﬂange screws to 5.9 N·m (52 in. lb.). Do not over tighten.

2. Connect the inlet, outlet, and pulse lines to their respective ﬁings on pump. Secure with the clamps. See Figure 5-1.

Section 5

Fuel System and Governor

WARNING: Explosive Fuel

Troubleshooting – Fuel System

If engine troubles are experienced that appear to be fuel system related, check the following areas before adjusting or disassembling the carburetor.

Figure 5-1. Pulse Fuel Pump.

Carburetor

These engines are equipped with a Walbro ﬁxed main jet carburetor. See Figure 5-2. The carburetors will have a low idle speed adjustment screw, and either ﬁxed idle, or a limiter cap on the idle fuel adjustment needle.

• Make sure the fuel tank is ﬁlled with clean, fresh gasoline.

• Make sure the fuel cap vent is not blocked and that it is operating properly.

• Make sure fuel is reaching the carburetor. This includes checking the fuel shut-oﬀ valve, fuel tank ﬁlter screen, in-line fuel ﬁlter, fuel lines, and fuel pump (as equipped), for restrictions or faulty components.

• Make sure the air cleaner base and carburetor are securely fastened to the engine using gaskets in good condition.

• Make sure the air cleaner element is clean, and all air cleaner components are fastened securely.

• Make sure the ignition system, governor system, exhaust system, and throle and choke controls are operating properly.

If, aer checking the items listed above, starting problems or conditions similar to those listed in the following table exist, it may be necessary to adjust or service the carburetor.

Figure 5-2. Carburetor.

5.3

Page 34

Section 5 Fuel System and Governor

Troubleshooting – Fuel System

Condition

1. Engine starts hard, runs roughly or stalls at idle speed.

2. Engine runs rich. (Indicated by black, sooty exhaust smoke, misﬁring, loss of speed and power, governor hunting, or excessive throle opening).

3. Engine runs lean. (Indicated by misﬁring, loss of speed and power, governor hunting, or excessive throle opening).

4. Fuel leaks from carburetor. 4a. Float level set too high. See Remedy 2c.

1a. Low idle fuel mixture/speed improperly adjusted. Adjust the low

idle speed screw, then adjust the low idle fuel needle.

b. Improper choke adjustment.

2a. Choke partially closed during operation. Check the choke lever/

linkage to ensure choke is operating properly.

b. Low idle fuel mixture is improperly adjusted. Adjust low idle

fuel needle.

c. Float level is set too high. With fuel bowl removed and carburetor

inverted, the exposed surface of ﬂoat must be parallel with the bowl gasket surface of the carburetor body.

d. Dirt under fuel inlet needle. Remove needle; clean needle and

seat and blow with compressed air.

e. Bowl vent or air bleeds plugged. Remove fuel bowl, low idle

fuel adjusting needle, and welch plugs. Clean vent, ports, and air

bleeds. Blow out all passages with compressed air. f. Fuel bowl gasket leaks. Remove fuel bowl and replace gasket. g. Leaky, cracked, or damaged ﬂoat. Submerge ﬂoat to check for

leaks.

3a. Low idle fuel mixture is improperly adjusted. Adjust low idle

fuel needle. b. Float level is set too low. With fuel bowl removed and carburetor

inverted, the exposed surface of ﬂoat must be parallel with the

bowl gasket surface of the carburetor body. c. Idle holes plugged; dirt in fuel delivery channels. Remove fuel

bowl, low idle fuel adjusting needle, and welch plugs. Clean

main fuel jet and all passages; blow out with compressed air.

b. Dirt under fuel inlet needle. See Remedy 2d. c. Bowl vent plugged. Remove fuel bowl and clean bowl vent. Blow

out with compressed air. d. Float is cracked or damaged. Replace ﬂoat. e. Bowl retaining screw gasket damaged. Replace gasket. f. Bowl retaining screw loose. Torque screw to speciﬁcations.

Possible Cause/Probable Remedy

Carburetor Adjustment

NOTE: Carburetor adjustments should be made only

aer the engine has warmed up.

The carburetor is designed to deliver the correct fuel-to-air mixture to the engine under all operating conditions. The main fuel jet is calibrated at the factory and is not adjustable. The idle fuel adjustment needle is also set at the factory and normally does not need adjustment. If the engine is hard starting or does not operate properly, however, it may be necessary to adjust or service the carburetor.

5.4

Idle Speed (RPM) Adjustment Screw

Idle Fuel Mixture Needle

Figure 5-3. Fixed Main Jet Carburetor.

Page 35

Section 5

Fuel System and Governor

Low Idle Mixture Adjustment*

NOTE: Engines will have ﬁxed idle (no adjustment

possible) or a limiter cap on the idle fuel adjustment needle. Step 2 can only be performed within the limits allowed by the cap.

1. Start the engine and run at half throle for 5 to 10 minutes to warm up. The engine must be warm before doing step 2.

2. Low Idle Fuel Needle Seing: Place the throle into the idle or slow position.

Turn the low idle fuel adjustment needle out

(counterclockwise) from the preliminary seing until engine speed decreases (rich). Note the position of the needle.

Now turn the adjusting needle in (clockwise).

The engine speed may increase, then it will decrease as the needle is turned in (lean). Note the position of the needle.

Set the adjusting needle midway between the rich

and lean seings. See Figure 5-4.

Low Idle Speed Setting

1. Start the engine and run at half throle for 5 to 10 minutes to warm up. The engine must be warm before doing step 2.

2. Low Idle Speed Seing: Place the throle control into the idle or slow position. Set the low idle speed by turning the low idle speed adjusting screw in or out. Check the speed using a tachometer.

NOTE: The actual low idle speed depends on

the application–refer to equipment manufacturer’s recommendations. The recommended low idle speed for basic engines is 1500 RPM. To ensure best results when seing the low idle fuel needle, the low idle speed must not exceed 1500 RPM (±75 RPM).

Lean

Adjust to Midpoint

Rich

Figure 5-4. Optimum Low Idle Fuel Setting.

*NOTE: If the engine is equipped with a governed idle

adjustment (See Figure 5-23), the governor will compensate for speed changes due to the low idle mixture adjustment. Disable the governed idle control by backing out the governed idle adjusting screw and seing a ﬁxed idle speed using the idle speed screw on the carburetor. Make the low idle mixture adjustment and then reset the governed idle speed at the adjusting screw.

5.5

Page 36

Section 5 Fuel System and Governor

Disassembly

Throttle Lever and Shaft

Dust Seal

Throttle Plate Screw(s)

Throttle Plate

Low Idle Speed Adjusting Screw and Spring

Low Idle Fuel Adjusting Needle and Spring with Limiter Cap

Choke Lever and Shaft

Choke Return Spring

Choke Plate

Fuel Inlet Needle

Float

Float Shaft

Bowl Gasket

Fuel Bowl

Fuel Shut-off Solenoid

Figure 5-5. Carburetor - Exploded View.

1. Remove the bowl retaining screw or fuel shut-oﬀ solenoid, retaining screw gasket, and fuel bowl.

2. Remove the bowl gasket, ﬂoat sha, ﬂoat, and fuel inlet needle.

3. Do not aempt to remove the low idle fuel adjustment needle if it has a limiter cap.

Further disassembly to remove the welch plugs,

main fuel jet, throle plate and sha, and choke plate and sha is recommended only if these parts are to be cleaned or replaced.

5.6

Bowl Retaining Screw Gasket

Welch Plug Removal

In order to clean the idle ports and bowl vent thoroughly, remove the welch plugs covering these areas.

Use SPX Tool No. KO-1018 and the following procedure to remove the welch plugs. See Figure 5-6.

1. Pierce the welch plug with the tip of the tool.

NOTE: To prevent damage to the carburetor, do

not allow the tool to strike the carburetor body.

2. Pry out the welch plug with the tip of the tool.

Bowl Retaining Screw

Page 37

Tool No. KO1018

Section 5

Fuel System and Governor

2. The choke plate is inserted into a slot in the choke sha. Grasp the choke plate with pliers, and pull it out of the slot. See Figure 5-8.

Do Not Allow Tip to Strike Carburetor Body

Figure 5-6. Removing Welch Plug.

Main Fuel Jet Removal

The main jet is pressed into the side of the tower portion of the body. Removal is not recommended, unless a high-altitude kit is being installed, in which case the removal instructions will be included in the kit.

Fuel Inlet Seat Removal

The fuel inlet seat is pressed into the carburetor body, do not aempt to remove it. If necessary, clean it in place with aerosol carburetor cleaner.

Choke Shaft Removal

1. Because the edges of the choke plate are beveled, mark the choke plate and carburetor body, to ensure correct reassembly. See Figure 5-7.

Also note the choke plate position in the bore,

and the position of the choke lever and choke return spring.

Pierce Plug with Tip

Pry Out Plug

Welch Plug

Figure 5-8. Removing Choke Plate.

3. Remove the choke sha and choke return spring.

Throttle Shaft Removal

Do not aempt to remove the throle sha, as repair kits are not available. Throle sha wear is normally accompanied by corresponding wear to the carburetor body, making it impractical to aempt a cost-eﬀective repair. Replace the entire carburetor if the throle sha is worn.

Cleaning

WARNING: Flammable Solvents!

Figure 5-7. Marking Choke Plate and Carburetor Body.

All parts should be cleaned thoroughly using a commercial carburetor cleaner. Make sure all gum deposits are removed from the following areas.

• Carburetor body and bore; especially the areas where the throle plate, choke plate and shas are seated.

• Idle fuel and idle ports in carburetor bore, main jet, bowl vent, and fuel inlet needle and seat.

• Float and ﬂoat hinge.

• Fuel bowl.

5.7

Page 38

Section 5 Fuel System and Governor

• Throle plate, choke plate, throle sha, and choke sha.

NOTE: Do not submerge the carburetor in

cleaner or solvent when plastic, ﬁber, rubber, foam seals or gaskets are installed. The cleaner may damage these components.

Inspection

Carefully inspect all components and replace those that are worn or damaged.

• Inspect the carburetor body for cracks, holes, and other wear or damage.

• Inspect the ﬂoat for cracks, holes, and missing or damaged ﬂoat tabs. Check the ﬂoat hinge and pin for wear or damage.

• Inspect the fuel inlet needle and seat for wear or damage.

• Inspect the tip of the low idle fuel adjustment needle for wear or grooves.

• Inspect the throle and choke sha and plate assemblies for wear or excessive play.

Repair

Always use new gaskets when servicing or reinstalling carburetors. Repair kits are available which include new gaskets and other components. Always refer to the Parts Manual for the engine being serviced to ensure the correct repair kits are ordered.

Reassembly

Choke Shaft Installation

1. Install the choke return spring to the choke sha.

Welch Plug Installation

Use SPX Tool No. KO1017 and install new plugs as follows:

1. Position the carburetor body with the welch plug cavities to the top.

2. Place a new welch plug into the cavity with the raised surface up.

3. Use the end of the tool that is about the same size as the plug and ﬂaen the plug. Do not force the plug below the surface of the cavity. See Figure 5-9.

Tool No. KO1017

Carburetor Body

Figure 5-9. Installing Welch Plugs.

4. Aer the plugs are installed, seal them with Glyptal™ (or an equivalent sealant). Allow the sealant to dry.

NOTE: If a commercial sealant is not available,

ﬁngernail polish can be used.

Carburetor Reassembly

1. Install the low idle speed adjusting screw and spring.

New Welch Plug

2. Insert the choke sha with the return spring into the carburetor body.

3. Rotate the choke lever approximately 1/2 turn counterclockwise. Make sure the choke return spring hooks on the carburetor body.

4. Position the choke plate as marked during disassembly. Insert the choke plate into the slot in the choke sha. Make sure the choke sha is locked between the tabs on the choke plate.

5.8

2. If the low idle fuel adjusting needle contains a limiter, adjust to the midpoint within the adjustment range.

3. Insert the fuel inlet needle into the ﬂoat. Align the needle with the seat and lower the ﬂoat into the carburetor body. See Figure 5-10. Install the ﬂoat sha.

Page 39

Section 5

Fuel System and Governor

Figure 5-10. Installing Float and Fuel Inlet Needle.

4. Install the bowl gasket, fuel bowl, bowl retaining screw gasket, and bowl retaining screw or fuel solenoid.

Torque the bowl retaining screw to 5.1-6.2 N·m

(45-55 in. lb.).

Fuel Shut-off Solenoid

Many engines are equipped with a fuel shut-oﬀ solenoid installed in place of the bowl retaining screw to eliminate backﬁring when the engine is shut down. If backﬁring occurs on engines equipped with this solenoid, verify that the correct shutdown procedure is being used. In order for the solenoid to be eﬀective, the engine must be running between half and full throle when the key is turned oﬀ. Next, check the baery to ensure that it is not discharged or faulty. A minimum of 7.3 volts DC is required to activate the solenoid. Also check to see that the ground lead from the carburetor body to the air cleaner base mounting screw is properly connected.

Figure 5-11. Fuel Shut-Off Solenoid.

High Altitude Operation

Operating the engine with the wrong engine conﬁguration at a given altitude may increase its emissions and decrease fuel eﬃciency and performance. To ensure correct engine operation at altitudes above 1219 meters (4000 ), it may be necessary to have an authorized Kohler dealer install a special high altitude jet kit in the carburetor. If a high altitude kit has been installed, the engine must be reconverted to the original jet size, before it is operated at lower altitudes, or overheating and engine damage can result.

To obtain high altitude kit information or locate a dealer near you, call 1-800-544-2444 to ﬁnd the names of the nearest Kohler Co. Service Centers or, access our web site at: www.kohlerengines.com and click on the “Service & Dealer Locator” located in the upper right hand corner. The service center will need your engine speciﬁcation number which is found on your Engine ID Label.

If these check out, the solenoid should be removed for bench testing. Remember to shut oﬀ the fuel supply and catch any fuel spilling from the carburetor as the solenoid is removed.

Bench test the solenoid by grounding the solenoid case and applying 12 volt DC to the spade terminal. If the plunger does not retract, the solenoid is faulty and must be replaced. Always use a new fuel bowl gasket whenever the solenoid is installed. Refer to the wiring diagram in Section 7 and connect the fuel shut-oﬀ solenoid.

Unitized Throttle and Choke Control

Some engines are equipped with a unitized throle and choke control. This assembly controls the choke and engine speed with a single lever. See Figure 5-12.

5.9

Page 40

Section 5 Fuel System and Governor

Throttle Cable Adjustment

1. Loosen the control cable clamp. See Figure 5-12.

Cable Clamp

Figure 5-12. Speed Control Bracket with Unitized Throttle/Choke Control.

2. Place the throle control lever of the equipment into the fast or high speed position. The actuating tab+ of the choke lever should be just below the end of the choke adjusting screw. See Figure 5-13.

Choke Adjustment Screw

Cold Engine

Figure 5-14. Typical Throttle/Choke Controls.

3. Early Models: Early models use a single

alignment hole to set the engine RPM. Align the hole in the throle lever with the hole in the speed control bracket by inserting a pencil or 6.35 mm (1/4 in.) drill bit. See Figure 5-15.

Alignment Hole

Figure 5-15. Alignment Hole in Speed Control Bracket and Throttle Lever. (Early Models)

Warm Engine

Figure 5-13Adjusting Unitized Throttle/Choke Control.

NOTE: The choke is placed on by moving the

throle control slightly past the fast position. If the throle control does not have a designated choke on position, be sure to leave suﬃcient throle control travel past the fast position. This will enable the choke to be placed on. See Figure 5-14.

5.10

Later Models: Later models use a new control

assembly, identiﬁed by two opposing alignment holes (close to the throle lever pivot), instead of one. Based upon the intended high-speed (RPM) seing, throle cable adjustment must be made by matching the hole in the control lever with the correct alignment hole. Use the lower (le side) hole for high-speed seings above 3000 RPM. Use the upper (right side) hole for high-speed seings lower than 3000 RPM. Move the throle lever to align the hole in the lever with the correct hole in the control bracket. Insert a pencil or a 6.35 mm (1/4 in.) drill bit to hold in position. See Figure 5-16.

Page 41

Section 5

Fuel System and Governor

4. Pull on the outer shield of the throle control cable to remove any slack. Tighten the cable clamp securely.

Alignment Hole

Alignment Hole for 3000 RPM and Higher

Figure 5-16. Alignment Holes in Speed Control Bracket and Throttle Lever. (Later Models)

Starting an Engine Equipped with Unitized Throttle and Choke Control

1. For a Cold or Warm Engine – Place the throle/ choke control into the fast/choke on position. This will also place the choke into the on position. See Figure 5-17.

for Less Than 3000 RPM

NOTE: If the engine develops suﬃcient speed

to disengage the starter but does not keep running (a false start), engine rotation must be allowed to come to a complete stop before aempting to restart the engine. If the starter is engaged while the ﬂywheel is rotating, the starter pinion and ﬂywheel ring gear may clash, resulting in damage to the starter.

If the starter does not turn the engine over, shut the starter oﬀ immediately. Do not make further aempts to start the engine until the condition is corrected. Do not jump start using another baery (refer to Baery, Section 7). See your Kohler Engine Service Dealer for trouble analysis.

4. For Operation – Aer the engine starts, move the throle/choke control from the fast/choke on position and set the desired engine operating speed (between the slow and fast position).

High Speed (RPM) Adjustment

The recommended maximum no-load high speed (RPM) for most engines is 3300 RPM. The actual high speed (RPM) depends on the application. Refer to the equipment manufacturer’s instructions for speciﬁc information.

Figure 5-17. Throttle Position for Starting Engine.

2. Make sure the equipment is in neutral.

3. Activate the starter switch. Release the switch as soon as the engine starts.

NOTE: Do not crank the engine continuously

for more than 10 seconds at a time. If the engine does not start, allow a 60 second cool down period between starting aempts. Failure to follow these guidelines can burn out the starter motor.

WARNING: Overspeed is Hazardous!

Do not tamper with the governor seing. Over speed is hazardous and could cause personal injury.

1. Make sure the throle cable is adjusted properly (see ‘Throle Cable Adjustment).

2. Start the engine and allow it to warm up. Place the throle control lever into the fast or high speed position. Turn the choke adjustment screw (see Figure 5-13) out/counterclockwise, so there is clearance from the choke lever, and that contact cannot occur during Step 4. See Figure 5-13.

3. Early Models: Early models use a single alignment hole to set the engine RPM. Align the hole in the throle lever with the hole in the speed control bracket by inserting a pencil or 6.35 mm (1/4 in.) drill bit. See Figure 5-15.

5.11

Page 42

Section 5 Fuel System and Governor

Later Models: Later models utilize a new design

control assembly, identiﬁed by two opposing alignment holes (close to the throle lever pivot), instead of one. Based upon the intended high speed (RPM) seing, throle cable adjustment must be made matching the hole in the control lever with the appropriate alignment hole. Use the lower (le side) hole for high-speed seings 3000 RPM and above. Use the upper (right side) hole for high-speed seings less than 3000 RPM. Move the throle lever to align the hole in the lever with the appropriate hole in the control bracket. Insert a pencil or a 6.35 mm (1/4 in) drill bit to hold in position. See Figure 5-16.

4. Loosen the speed control bracket mounting screws. Slide the bracket forward or backward, until the desired high speed (RPM) is reached. See Figure 5-18. Check the speed with a tachometer.

Choke Adjustment

This procedure must follow the High Speed Adjustment just described. If not already completed, perform that operation ﬁrst.

1. Turn the choke adjusting screw out

(counterclockwise), until it no longer contacts the choke lever.

2. Then turn it back in (clockwise), until it just

makes contact.

3. While observing the choke link, move the throle control lever to the low idle (slow) position, then back to full throle (fast). The choke link should not move as the throle moves through the normal range. If it does, back the adjusting screw out until it no longer moves.

4. Move the throle control lever to the choke position. Check if the choke has fully closed by placing your ﬁnger on the right side of the lower end of the choke lever/choke link and applying gentle pressure towards the carburetor. If the controls have been properly set, the link should not move.

Figure 5-18. Adjusting High Speed (RPM).

To increase the high speed (RPM), move the

bracket toward the carburetor.

To decrease the high speed (RPM), move the

bracket away from the carburetor.

5. Tighten the speed control bracket mounting screws. Recheck the speed with a tachometer and readjust if necessary.

Torque the mounting screws as follows:

Into new as-cast hole – 11.0 N·m (95 in. lb.). Into used hole – 7.5 N·m (65 in. lb.).

6. Adjust the choke (see Choke Adjustment which follows).

Separate Throttle and Choke Control

Some engines are equipped with separate throle and choke controls. This allows you to adjust the choke and throle controls individually.

Install Separate Control Cables

Throttle Control Installation

1. Loosen the two cable clamp screws on the speed control bracket assembly. See Figure 5-19.

2. Move the application throle control lever to the maximum full (fast) throle position, and then move it back 3/16" or 4.75 mm. Insert the cable boden wire into the throle control lever on the control plate.

3. Position the throle cable under the cable clamp.

5.12

Page 43

Choke Cable Clamp

Section 5

Fuel System and Governor

5. Pull on the outer shield of the throle control cable to remove any slack. Tighten the cable clamp securely.

Throttle Cable Clamp

Figure 5-19. Separate Choke and Throttle Cable Controls.

4. Early Models: Early models use a single

alignment hole to set the engine RPM. Align the hole in the throle lever with the hole in the speed control bracket by inserting a pencil or 6.35 mm (1/4 in.) drill bit. See Figure 5-20.

Alignment Hole

Alignment Hole for 3000 RPM and Higher

Figure 5-21. Alignment Holes in Speed Control Bracket and Throttle Lever. (Later Models)

6. Move the application throle lever to the slow position, then to full throle. Check the engine control to ensure it stops against the stop screw, which means it is properly set.

Choke Control Installation

1. Connect the choke cable boden wire to the engine choke control lever on the speed control bracket assembly.

2. Position the choke cable under the cable clamp.

3. Push/move the choke control to the oﬀ position in the application panel until it booms, then pull it back approximately 1/16 in.

for Less Than 3000 RPM

Figure 5-20. Alignment Hole in Speed Control Bracket and Throttle Lever. (Early Models)

Later Models: Later models utilize a new design

4. Push on the choke cable, ahead of the clamp on the engine control plate, until the choke lever stops. Do not force. Then tighten the cable clamp screw.

5. Move the choke control until it stops (on position). Check that the choke link cannot be moved towards the carburetor by applying ﬁnger pressure on the lower link/lever below the engine control plate. If the choke link moves, readjust by following steps 3 and 4.

6. Push/move the choke control in/down until it booms. The choke lever and link should be to the right at the end of its travel, with linkage free so the engine does not run on partial choke.

5.13

Page 44

Section 5 Fuel System and Governor

Starting an Engine Equipped with Separate Control Cables

1. Place the throle control midway between the slow and fast positions. Place the choke control

into the on position.

2. Start the engine.

3. For a Cold Engine – Gradually return the choke control to the oﬀ position aer the engine starts and warms up.

The engine/equipment may be operated during

the warm up period, but it may be necessary to leave the choke partially on until the engine warms up.

4. For a Warm Engine – Return choke to oﬀ position as soon as engine starts.

Changing the High Speed (RPM) on the Engines with Separate Controls (Increase or Decrease RPM)

1. Check that the governor spring and installation matches the intended high speed RPM operating range. Refer to Figure 5-27 or 5-28.

4. To ensure that the RPM has been obtained, move the throle lever to low idle/slow then back to full throle/fast position and check the RPM with a tachometer.

Setting the Low Idle RPM

1. Move the application control to slow position.

2. Using a tachometer, check the RPM. Then, using a screwdriver, turn the low idle speed screw (see Figure 5-3) inward (clockwise) to increase the RPM, and outward (counterclockwise) to lower the RPM.

Governed Idle Adjustment

A governed idle control system was supplied as a option on early engines and is standard on later model engines. The purpose of this system is to maintain a desired idle speed regardless of ambient conditions (temperature, parasitic load, etc.) that may change. The later models can be identiﬁed by the two opposing alignment holes, (adjacent from the throle lever pivot) rather than one. Based upon the intended high speed (RPM) seing, cable adjustment must be made matching the hole in the control lever with the appropriate alignment hole.

2. Start the engine, move the application throle lever to full throle/fast, and loosen the mounting screws of the main speed control bracket to allow repositioning. See Figure 5-22.

Figure 5-22. Adjusting High Speed (RPM).

3. To increase the RPM: Move the speed control

bracket, towards the carburetor. To decrease the RPM: Move the speed control bracket, away from the carburetor. Check the RPM with a tachometer and tighten screws when correct seing has been obtained. See Figure 5-19.

The system requires an additional procedure for seing the idle speed. If speed adjustments are required proceed as follows.

1. Make any necessary speed or control adjustments following the appropriate instructions already covered in this section.

2. Move the throle control to the idle position. Hold the governor lever away from the carburetor, so the throle lever is tight against the idle speed adjusting screw. Check the speed with a tachometer and adjust it to 1500-1750 RPM.

3. Release the governor lever and allow the engine to return to the governed idle speed. Check it with a tachometer against the equipment manufacturers recommended idle speed. If adjustment is necessary, use the governed idle adjusting screw on the speed control assembly (see Figure 5-23). Turn the screw clockwise to increase the governed idle speed and counterclockwise to decrease it.

5.14

Page 45

Governed Idle Adjusting Screw

Figure 5-23. Location of Governed Idle Adjusting Screw.

Governor

These engines are equipped with a centrifugal ﬂyweight mechanical governor, designed to hold the engine speed constant under changing load conditions. The governor gear/ﬂyweight mechanism is mounted on the closure plate in the crankcase, and is driven oﬀ a gear on the cranksha.

NOTE: Flyweights must be installed perpendicular

to the nylon gear as shown. Improper installation of the ﬂyweights may cause damage to the governor gear. See Figure 5-24.

Section 5

Fuel System and Governor

The governor lever is clamped on the protruding end of the sha and connected with linkage to the throle lever on the carburetor, so any rotation of the sha causes corresponding movement of the throle plate.

When the engine is at rest, and the throle is in the fast position, the tension of the governor spring holds the throle plate open. When the engine is operating (the governor gear assembly is rotating), the force applied by the regulating pin against the cross sha tends to close the throle plate. The governor spring tension and the force applied by the regulating pin are in equilibrium during operation, holding the engine speed constant.

When load is applied and the engine speed (and governor gear speed) decreases, the governor spring tension moves the governor arm to open the throle plate wider. This allows more fuel into the engine; increasing engine speed. This action takes place very rapidly, so a reduction in speed is hardly noticed. As the speed reaches the governed seing, the governor spring tension and the force applied by the regulating pin will again be in equilibrium. This maintains the engine speed at a relatively constant level.

The governed speed seing is determined by the position of the throle control. It can be variable or constant, depending on the application.

Flyweights

Nylon Gear

Figure 5-24. Governor Gear/Flyweight Assembly.

Operation

As the governor gear rotates, centrifugal force causes the ﬂyweights to move outward as speed increases. As the ﬂyweights move outward, they cause the regulating pin to move outward.

The regulating pin contacts the tab on the cross sha, causing the sha to rotate. One end of the cross sha protrudes through the side of the crankcase.

Initial Adjustment

Make this initial adjustment whenever the governor arm is loosened or removed from the cross sha. To ensure proper seing, make sure the throle linkage is connected to the governor arm and the throle lever on the carburetor. See Figures 5-25 and 5-26.

1. Move the governor lever toward the carburetor

(wide open throle). Do not apply excess force ﬂexing or distorting the throle link.

2. Grasp the cross sha with pliers, and turn the

sha counterclockwise as far as it will go, then tighten the hex nut. Torque the hex nut to

7.0-8.5 N·m (60-75 in. lb.).

5.15

Page 46

Section 5 Fuel System and Governor

Figure 5-25. Governor Adjustment.

Governor Sensitivity Adjustment

Governor sensitivity is adjusted by repositioning the governor spring in the holes in the governor lever. If speed surging occurs with a change in load, the governor is set too sensitive. If a big drop in speed occurs when a normal load is applied, the governor should be set for greater sensitivity.

The desired high speed seing (RPM) will determine the governor spring position in the governor lever and the throle lever, as well as the spring used. See Figure 5-27 and 5-28.

Throttle Lever

Governor Lever

Figure 5-26. Tightening Governor Lever Nut.

Single Alignment Hole

High Speed

RPM

   ;

    ;

Figure 5-27. Early Style Governor Spring Location Chart.

5.16

Governed

Idle RPM

Governed

Lever Hole No.

Throttle Lever

Hole No.

White

Spring

Green

Spring

Black

Spring

Page 47

Section 5

Fuel System and Governor

Single Hole

Throttle Lever

/HVVWKDQ530 6LQJOH+ROH  ; %

/HVVWKDQ530 6LQJOH+ROH  ; $

Figure 5-28. Later Style Governor Spring Location Chart.

Governor Lever (Single Hole)

High Speed

RPM

Governed

Idle RPM

Governor Lever (Multiple Hole)

Governed

Lever Hole No.

Alignment Hole for 3000 RPM and Higher

Throttle Lever

Hole No.

Red

Spring

Alignment Hole for Less Than 3000 RPM

Alignment

Hole

5.17

Page 48

Section 5 Fuel System and Governor

5.18

Page 49

Section 6

Lubrication System

Oil Recommendations

Using the proper type and weight of oil in the crankcase is extremely important. So is checking oil daily and changing oil regularly. Failure to use the correct oil, or using dirty oil, causes premature engine wear and failure.

Oil Type

Use high-quality detergent oil of API (American Petroleum Institute) service class SJ or higher. Select

the viscosity based on the air temperature at the time of operation as shown in the following table.

RECOMMENDED SAE VISCOSITY GRADES

10W-30

5W-20, 5W-30

Section 6

Lubrication System

SAE

10W-30

Figure 6-2. Oil Container Logo.

Check Oil Level

The importance of checking and maintaining the proper oil level in the crankcase cannot be overemphasized. Check oil BEFORE EACH USE as follows:

Kohler 10W-30

°F -20 0 20 32 40 60 80 100

°C -30 -20 -10 0 10 20 30 40

TEMPERATURE RANGE EXPECTED BEFORE NEXT OIL CHANGE

* Use of synthetic oil having 5W-20 or 5W-30 rating is acceptable,

up to 4°C (40°F)

** Synthetic oils will provide better starting in extreme cold below

23°C (-10°F)

Figure 6-1. Viscosity Grades Table.

NOTE: Using other than service class SG, SH, SJ or

higher oil or extending oil change intervals longer than recommended can cause engine damage.

NOTE: Synthetic oils meeting the listed

A logo or symbol on oil containers identiﬁes the API service class and SAE viscosity grade. See Figure 6-2.

1. Make sure the engine is stopped, level, and is cool so the oil has had time to drain into the sump.

2. To keep dirt, grass clippings, etc., out of the engine, clean the area around the oil ﬁll cap/ dipstick before removing it.

3. Remove the oil ﬁll cap/dipstick; wipe oil oﬀ. See Figure 6-3. Reinsert the dipstick into the tube and fully seat the dipstick in the tube. See Figure 6-4.

Figure 6-3. Removing Dipstick.

6.1

Page 50

Section 6 Lubrication System

Oil Filter

Oil Drain Plug

Figure 6-4. Dipstick Seated.

4. Remove the dipstick and check the oil level. The oil level should be up to, but not over the ‘‘F’’ mark on the dipstick. See Figure 6-5.

Operating Range

Figure 6-5. Oil Level Dipstick.

5. If the level is low, add oil of the proper type, up to the ‘‘F’’ mark on the dipstick. Always check the level with the dipstick before adding more oil.

NOTE: To prevent extensive engine wear or

damage, always maintain the proper oil level in the crankcase. Never operate the engine with the oil level below the ‘‘L’’ mark or over the ‘‘F’’ mark on the dipstick.

Change Oil and Oil Filter

Change the oil and oil ﬁlter annually or every 100 hours of operation. Change the oil and oil ﬁlter while

the engine is still warm. The oil will ﬂow more freely and carry away more impurities. Make sure the engine is level when ﬁlling or checking oil. Change the oil and ﬁlter as follows (see Figure 6-6). Always use a genuine Kohler oil ﬁlter.

Figure 6-6. Oil Drain Plug, Oil Filter.

1. To keep dirt, grass clipping, etc., out of the engine, clean the area around the oil ﬁll cap/ dipstick before removing it.

2. Remove the drain plug and oil ﬁll cap/dipstick. Be sure to allow ample time for complete drainage.

3. Remove the old ﬁlter and wipe oﬀ the mounting pad.

4. Reinstall the oil drain plug and torque to 14 N·m (125 in. lb.).

5. Place the new replacement ﬁlter in a shallow pan with the open end up. Pour new oil of the proper type, in through the threaded center hole. Stop pouring when the oil reaches the boom of the threads. Allow a minute or two for the oil to be absorbed by the ﬁlter material.

6. Apply a thin ﬁlm of clean oil to the rubber gasket on the new ﬁlter.

7. Install the new oil ﬁlter to the ﬁlter adapter or oil cooler. Refer to instructions on the oil ﬁlter for proper installation.

8. Fill the crankcase with new oil of the proper type, to the “F” mark on the dipstick.

9. Reinstall the oil ﬁll cap/dipstick and push ﬁrmly into place.

10. Test run the engine to check for leaks. Stop the engine, allow a minute for the oil to drain down, and recheck the level on the dipstick. Add more oil, as necessary, so the oil level is up to but not over the “F” mark.

6.2

Page 51

Section 6

Lubrication System

NOTE: To prevent extensive engine wear or

damage, always maintain the proper oil level in the crankcase. Never operate the engine with the oil level below the ‘‘L’’ mark or over the ‘‘F’’ mark on the dipstick.

Full-Pressure Lubrication System

Operation

This engine uses a full-pressure lubrication system to deliver oil for internal lubrication. A cam driven, high eﬃciency Gerotor™ oil pump located in the crankcase maintains proper oil ﬂow and oil pressure even at low speeds and high operating temperatures. Oil is supplied from the pump via two circuits to the cranksha main bearings, cranksha, connecting rod bearing surfaces, cam gears, and axis shas. An integral pressure relief valve within the oil pump limits the maximum pressure of the system.

For a cold engine at start up, the oil pressure can go up to 20-25 psi. For a warm (normal operating temperature) engine at idle speed, the oil pressure can go down to 5 psi.

Service

The oil pump rotors typically require no servicing, if normal maintenance is performed as outlined in Section 1.

The closure plate must be removed for access to the oil pump and the rotors. Refer to the Disassembly and Reassembly, Sections (8 and 10), for removal and reinstallation procedures.

Oil Filter

These engines are equipped with a full-ﬂow oil ﬁlter. See Figure 6-8.

The oil ﬁlter helps remove sludge and other combustion by-products from the oil. It also extends the oil change interval and cools the oil.

Oil Filter

Figure 6-8. Oil Filter Location.

Oil Sentry™

Some engines are equipped with an optional Oil Sentry™ switch. This switch is designed to prevent the engine from starting in a low oil or no oil condition. The Oil Sentry™ may not shut down a running engine before damage occurs. In some applications this switch may activate a warning signal. Read your equipment manuals for more information.

Operation

The pressure switch is designed to break contact as the oil pressure increases and make contact as the oil pressure decreases. At oil pressure above approximately 2 to 5 psi, the switch contacts open. At oil pressures below approximately 2 to 5 psi, the switch contacts close.

Figure 6-7. Oil Pump on Intake Cam Shaft (Gerotors Removed from Pump Housing).

On vehicular applications (lawn tractors, mowers, etc.), the pressure switch can be used to activate a low oil warning light. On stationary or unaended applications, the pressure switch can be used to ground the ignition module to stop the engine.

NOTE: Oil Sentry™ is not a substitute for checking

the oil level BEFORE EACH USE. Make sure the oil level is maintained up to the ‘‘F’’ mark on the dipstick. See Figure 6-5.

6.3

Page 52

Section 6 Lubrication System

Installation

The pressure switch is installed into the center oil galley of the ﬁlter adapter casting on the closure plate. Based on the application an elbow adapter may also be used. See Figure 6-9. On engines not equipped with

™

Oil Sentry

, the oil galley is sealed with a 1/8" pipe

plug or completely sealed.

™

Oil Sentry (External)

™

Oil Sentry Blower Housing)

(Behind

Figure 6-9. Oil Sentry™ Pressure Switch Locations.

To install the Oil Sentry™ switch:

1. Remove and discard the pipe plug from the center passage of oil ﬁlter mounting pad.

2. Apply pipe sealant with Teﬂon® (Loctite® No. 59241 or equivalent) to the threads of the 90° adapter (if used), and the Oil Sentry™ switch.

1. Connect the continuity tester across the blade terminal and the metal case of the switch. With 0 psi pressure applied to the switch, the tester should indicate continuity (switch closed).

2. Gradually increase the pressure to the switch. The tester should indicate a change to no continuity (switch open) as the pressure increases through the range of 2.0/5.0 psi.

The switch should remain open as the pressure is

increased to 90 psi maximum.

3. Gradually decrease the pressure to the switch. The tester should indicate a change to continuity (switch closed) as the pressure decreases through the range of 2.0/5.0 psi; approaching 0 psi.

If the switch does not operate as speciﬁed,

replace the switch.

Testing Oil Pressure

On some models the engine oil pressure can be tested using an oil pressure tester. Follow the instructions included with the tester. The pressure can be tested by removing the oil ﬁlter and installing the tester adapter on the mounting pad, or by removing the Oil Sentry pressure switch (or pipe plug) and threading the tester hose directly into the mounting hole. See Figure 6-10.

™

3. Install the adapter (if used), and carefully tighten it to the intended position. Do not over tighten or damage the adapter.

4. Install the switch into the adapter or center passage. Torque the switch to 4.5-5.0 N·m (40-45 in. lb.).

5. Connect the lead to the terminal on the Oil Sentry™ switch.

Testing the Oil Sentry™ Switch

The Oil Sentry™ pressure monitor is a normally closed switch. It is calibrated to open (break contact) with increasing pressure and close (make contact) with decreasing pressure within the range of 2.0/5.0 psi.

Compressed air, a pressure regulator, pressure gauge, and a continuity tester are required to test the switch.

6.4

Locations For Tester

Figure 6-10. Tester Locations (Some Models).

Page 53

Section 7

Electrical System and Components

Section 7

Electrical System and Components

This section covers the operation, service, and repair of the electrical system and electrical system components.

Major electrical systems and components covered in this section include the ignition system, baery, baery charging systems, electric starter, and optional Oil Sentry™ oil level pressure switch.

WARNING: Electrical Shock

Never touch electrical wires or components while the engine is running. They can be sources of electrical shock.

Spark Plug

Engine misﬁre or starting problems are oen caused by a spark plug that is in poor condition or has an improper gap seing.

The engine is equipped with the following spark plug:

Type: Champion® RC12YC or QC12YC (RFI Compliant)

Gap 0.76 mm (0.030 in.) Thread Size: 14 mm Reach: 19.1 mm (3/4 in.) Hex Size: 15.9 mm (5/8 in.)

Spark Plug Service

Annually or every 100 hours of operation, remove the spark plug. Check its condition, and reset the gap or replace with a new plug as necessary. Spark plug replacement is recommended at 500 hours.

1. Before removing the spark plug, clean the area around the base of the plug to keep dirt and debris out of the engine. Due to the deep recess around the spark plug, blowing out the cavity with compressed air is usually the most eﬀective method for cleaning. The spark plug is most accessible when the blower housing is removed for cleaning.

2. Remove the plug and check its condition. Replace the plug if worn or reuse is questionable.

NOTE: Do not clean the spark plug in a machine

using abrasive grit. Some grit could remain in the spark plug and enter the engine, causing extensive wear and damage.

3. Check the gap using a wire feeler gauge. Adjust the gap by carefully bending the ground electrode. Gap plugs to 0.76 mm (0.030 in.). See Figure 7-1.

Wire Gauge

Spark Plug

0.76 mm

Ground Electrode

Figure 7-1. Servicing Spark Plug.

4. Reinstall the spark plug into the cylinder head.

Torque the spark plug to 24-30 N·m (18-22 . lb.).

5. Reconnect the spark plug lead and reinstall the blower housing, if removed previously. Torque the blower housing screws to 7.7 N·m (68.3 in. lb.).

(0.030 in. ) Gap

7.1

Page 54

Section 7 Electrical System and Components

Inspection

Inspect the spark plug as soon as it is removed from the cylinder head. The deposits on the tip are an indication of the general condition of the piston rings, valves, and carburetor.

Normal and fouled plugs are shown in the following photos.

Chalky White Deposits: Chalky white colored deposits indicate overheating. This condition is usually accompanied by excessive gap erosion. A clogged grass screen, clogged cooling ﬁns, and lean carburetion are some causes of overheating.

Normal: A plug taken from an engine operating under normal conditions will have light tan or gray colored deposits. If the center electrode is not worn, a plug in this condition could be regapped and reused.

Worn: On a worn plug, the center electrode will be rounded and the gap will be eroded .010" or more than the correct gap. Replace a worn spark plug immediately.

Carbon Fouled: So, sooty, black deposits indicate incomplete combustion. Incomplete combustion is usually caused by over-rich carburetion, weak ignition, or poor compression.

7.2

Wet Fouled: A wet plug is caused by excess fuel, or oil in the combustion chamber. Excess fuel could be caused by operating the engine with too much choke or a dirty air ﬁlter. Oil in the combustion chamber is usually caused by worn piston rings or valve guides.

Page 55

Electronic CD Ignition System

Air Gap

0.203/0.305 mm (0.008-0.012 in.)

Electrical System and Components

Ignition Module

Spark Plug Boot

Spark Plug

Section 7

Spark Plug Terminal (C)

Flywheel

Kill Switch or Off Position of Key Switch

Figure 7-2. Electronic CD Ignition System.

These engines are equipped with a dependable electronic, capacitive discharge (CD) ignition system. The system consists of the following components:

• A magnet assembly which is permanently aﬃxed to the ﬂywheel.

• An electronic, capacitive discharge ignition module which mounts on the engine crankcase.

Magnet

Lamination (A)

• A spark plug.

• A kill switch (or key switch), which grounds the module to stop the engine.

Kill Terminal (B)

7.3

Page 56

Section 7 Electrical System and Components

SCS

Figure 7-3. Capacitive Discharge Ignition Module.

Operation

As the ﬂywheel rotates, and the magnet passes the ignition module, the magnetic ﬁeld induces current in the input coil (L1). The current pulse is rectiﬁed by a diode (D1) and charges a high-voltage capacitor (C1). As the magnet completes its pass, it induces current in a small triggering coil (L2), which turns on the semiconductor switch (SCS). With the switch on, the charged capacitor is directly connected to the primary winding (P) of the transformer (T1). As the capacitor discharges through the primary, the current initiates a fast-rising ﬂux ﬁeld in the transformer core. The ﬂux ﬁeld induces a high voltage in the secondary winding (S) of the transformer. The high voltage pulse is delivered to the spark plug, where it arcs across the electrode gap and ignites the fuel-air mixture in the combustion chamber.

Troubleshooting and Testing CD Ignition Systems

The CD ignition system is designed to be trouble free for the life of the engine. Other than periodically checking/replacing the spark plug, no maintenance or timing adjustment is necessary or possible. The ignition module automatically controls the timing of the spark. Mechanical systems do occasionally fail or break down, however, so the following troubleshooting information is provided to help systematically determine the cause of a reported problem.

Reported ignition problems are most oen due to poor or loose connections. Before beginning the test procedure check all external wiring, including ground leads for wiring harness and rectiﬁer-regulator (if so equipped). Be certain all ignition-related wires are connected, including the spark plug lead, and all terminal connections ﬁt snugly. Make sure the ignition switch is in the run position.

NOTE: The CD ignition systems are sensitive to

Preliminary Test

To be certain the reported problem is in the engine ignition system, it should be isolated from the unit, as follows.

1. Locate the plug connectors where the wiring

a. If the problem is gone, the electrical system

b. If the problem persists, continue with the

Spark Plug

excessive load on the kill lead. Customer complaints of hard starting, low power, or misﬁre under load may be due to excessive draw on the kill circuit. Disconnect any auxiliary kill wires or safety switches connected to the kill circuit and operate the engine to determine if the reported problem is gone.

harnesses from the engine and unit are joined. Separate the connectors and separate the white kill lead from the engine connector. Rejoin the connectors and position or insulate the kill lead terminal, so it cannot touch ground. Try to start the engine to verify whether the reported problem is still present.

on the unit is suspect. Check the key switch, wires, connections, safety interlocks, etc.

following troubleshooting procedure. Leave the kill lead isolated until all testing is completed.

7.4

Page 57

Electrical System and Components

CD Ignition System Troubleshooting Guide

7KHIROORZLQJJXLGHZLOOKHOSORFDWHDQGFRUUHFWLJQLWLRQV\VWHPSUREOHPV

Problem Test

1. Make sure the spark plug lead is connected to the spark plug.

Engine

Will Not

Start

2. Check the condition of spark plug. Make sure gap is set to 0.76 mm (0.030 in.).

3. a. Test for spark with ignition tester (See Section 2).

Disconnect spark plug lead and connect it to

the post terminal of the tester. See Figure 7-4. Connect the clip to a good ground, not the spark plug.

NOTE: To maintain engine speeds normally

obtained during cranking, do not remove the engine spark plug.

b. Make sure the engine ignition switch,

kill switch, or key switch is in the ‘‘run’’ position.

c. Crank the engine (minimum speed 500

RPM), and observe the tester. Visible and audible sparks should be produced.

2. If plug is in good condition, check/adjust gap and reinstall.

3. If visible and audible sparks are produced, the ignition module is OK.

If visible and audible sparks are not

produced:

a. Make sure the engine ignition switch,

b. Check wires and terminals of ignition

c. If wires and terminals are OK, the

Section 7

Conclusion

kill switch, or key switch is in the ‘‘run’’ position.

module and other components for accidental grounding and damaged insulation.

ignition module is probably faulty and should be replaced. Test module further using an ohmmeter (Test 4).

4. Measure the resistance of module secondary using an ohmmeter (see Figures 7-2 and 7-5):

Zero ohmmeter before testing. Connect

one ohmmeter lead to laminations (A). Connect the other lead to the spark plug terminal (C) of high-tension lead. With the ohmmeter leads connected in this manner, the resistance of secondary should be 7,900 to 18,400 ohms.

NOTE: This test cannot be performed

unless module has been ﬁred at least once.

4. If the resistance is low or 0 ohms, the

module secondary is shorted. Replace the module.*

If the resistance is high or inﬁnity ohms,

the module secondary is open. Replace the module.*

If the resistance is within the speciﬁed

range, the module secondary is OK.

*Refer to the Disassembly and Reassembly

Sections for complete ignition module removal and installation procedures.

Figure 7-4. Ignition Tester (See Section 2).

Figure 7-5. Testing CD Ignition Module Secondary.

7.5

Page 58

Section 7 Electrical System and Components

Battery

A 12 volt baery with a minimum current rating of 250 cold cranking amps is recommended. The actual cold cranking amp requirement depends on engine size, application and starting temperatures. As temperatures decrease, cranking requirements increase but baery capacity shrinks. Refer to the operating instructions of the equipment this engine powers for speciﬁc baery requirements.

If the baery charge is not suﬃcient to crank the engine, recharge the baery. Do not jump start using another baery.

Battery Charging

WARNING: Explosive Gases!

Before disconnecting the negative (-) ground cable, make sure all switches are OFF. If ON, a spark will occur at the ground cable terminal, which could cause an explosion if hydrogen gas or gasoline vapors are present.

Battery Maintenance

Regular maintenance will ensure the baery will accept and hold a charge.

1. Regularly check the level of electrolyte. Add distilled water as necessary to maintain the recommended level.

Battery Test

Test the baery voltage by connecting a DC voltmeter across the baery terminals and cranking the engine. If the baery drops below 9 volts while cranking, the baery is discharged or faulty. Refer to Figure 7-6.

DC Voltmeter

Battery

Figure 7-6. Checking Battery Voltage.

Electrical Systems Wiring Diagrams and Battery Charging Systems

Most engines are equipped with either a 9 or 15 amp, regulated baery charging system. Some have a 3 amp, regulated system with a 70 wa lighting circuit.

Refer to the following wiring diagrams and troubleshooting guides to test and service the system.

NOTE: Observe the following guidelines to

prevent damage to the electrical system and components.

1. Make sure the baery polarity is correct. A negative (-) ground system is used.

NOTE: Do not overﬁll the baery. Poor

performance or early failure due to loss of electrolyte will result.

2. Keep the cables, terminals, and external surfaces of the baery clean. A build-up of corrosive acid or grime on the external surfaces can selfdischarge the baery. Self-discharging happens rapidly when moisture is present.

3. Wash the cables, terminals, and external surfaces with a baking soda and water solution. Rinse thoroughly with clear water.

NOTE: Do not allow the baking soda solution to

enter the cells of the baery, as this will destroy the electrolyte.

7.6

2. Disconnect the baery cables (negative (-) cable ﬁrst), before doing electric welding on the equipment powered by the engine.

3. Prevent the stator leads from touching or shorting while the engine is running. This could damage the stator.

Page 59

Lighting Lead (Yellow)

Lighting Stator

Charging Lead (Black)

Figure 7-7. 3 Amp/70 Watt Stator.

Section 7

Electrical System and Components

3 Amp Charging Stator

Diode

Ground-ToKill Lead

Key Switch

Optional Oil Sentry Shutdown

Optional Fuse

Optional Oil Sentry Switch (Indicator Light)

Engine Connector

White

B+

RegulatorRectiﬁer

Violet

Green

Stator

Flywheel

Ignition Module

Spark Plug

(Red)

Optional Fuel Solenoid

Battery

Figure 7-8. 3 amp Regulated Battery Charging System/70 Watt Lighting.

Starter Solenoid

Optional Oil Sentry™ Switch (Shutdown or

Indicator) Bendix Starter

7.7

Page 60

Section 7 Electrical System and Components

Troubleshooting Guide 3 Amp Battery Charging System With 70 Watt Lighting Stator

NOTE: Zero ohmmeteres on each scale to ensure accurate readings. Voltage tests should be made with engine

running at full throle - no load. Baery must be fully charged.

Problem Test

1. With engine running in the fast seing, measure voltage across baery terminals using a DC voltmeter.

2. Remove connector from rectiﬁer-regulator. With engine running in the fast position, measure AC voltage across stator leads using an AC voltmeter.

3. With charging lead disconnected from baery and engine stopped, measure resistance from charging lead to ground

Charge

Battery

using an ohmmeter. Note reading.

Reverse the leads and measure resistance

again.

In one direction, the resistance should

be inﬁnity ohms (open circuit). With the leads reversed, some resistance should be measured (about midscale on Rx1 range).

4. Cut the sleeving on the charging lead to expose the diode connections.

Measure the resistance from the stator side

of diode to ground using an ohmmeter.

Conclusion

1. If voltage is more than 12.5 volts, charging

system is OK.

If voltage is 12.5 volts or less, the stator or

diode are probably faulty. Test the stator and diode (Test 2, 3, and 4).

2. If voltage is 20 volts or more, stator

winding is OK.

If voltage is less than 20 volts, test stator

using an ohmmeter (Tests 3 and 4).

3. If resistance is low in both directions, the

diode is shorted. Replace the diode.

If resistance is high in both directions, the

diode or stator winding is open. (Use

Test 4).

4. If resistance is approximately 0.5 ohms,

stator winding is OK, diode is open. Replace diode.

If resistance is 0 ohms, stator winding is

shorted. Replace stator.

1. Make sure lights are not burned out.

2. Disconnect the lighting lead from the wiring harness.

Lights

7.8

With engine running at in the fast seing,

measure voltage from lighting lead to ground using an AC voltmeter.

3. With engine stopped, measure the resistance of stator from lighting lead to ground using an ohmmeter.

If resistance is inﬁnity ohms, stator

winding or lead is open. Replace stator.

1. Replace burned out lights.

2. If voltage is 13 volts or more, stator is OK.

Check for loose connections or shorts in wiring harness.

If voltage is less than 13 volts, test stator

using an ohmmeter (Test 3).

3. If resistance is approximately 0.2 ohms,

stator is OK.

If resistance is 0 ohms, stator is shorted.

Replace stator.

If resistance is inﬁnity ohms, stator or

lighting lead is open. Replace stator.

Page 61

Section 7

Electrical System and Components

Troubleshooting Guide 3 Amp/70 Watt Braking Stator

NOTE: Zero ohmmeteres on each scale to ensure accurate readings. Voltage tests should be made with engine

running at full throle - no load. Baery must be fully charged.

Problem

Charge

Battery

Test

1. With engine running in the fast seing, measure voltage across baery

terminals using a DC voltmeter.

2. Remove connector from rectiﬁer-regulator. With engine running in the fast position, measure AC voltage across stator leads using an AC voltmeter.

3. With charging lead disconnected from baery and engine stopped, measure resistance from charging lead to ground using an ohmmeter. Note reading.

Reverse the leads and measure resistance

again.

In one direction, the resistance should

be inﬁnity ohms (open circuit). With the leads reversed, some resistance should be measured (about midscale on Rx1 range).

4. Disconnect the lighting lead (yellow) from the wiring harness.

Measure the resistance from the lighting

lead to ground using an ohmmeter.

Conclusion

1. If voltage is more than 12.5 volts, charging

system is OK.

If voltage is 12.5 volts or less, the stator or

diode are probably faulty. Test the stator and diode (Test 2, 3, and 4).

2. If voltage is 5 volts or more, stator winding

is OK.

If voltage is less than 5 volts, test stator

using an ohmmeter (Tests 3 and 4).

3. If resistance is low in both directions, the

diode is shorted. Replace the diode.

If resistance is high in both directions, the

diode or stator winding is open.

(Use Test 4.)

4. If resistance is approximately 0.15 ohms,

stator winding is OK, diode is open. Replace diode.

If resistance is 0 ohms, stator winding is

shorted. Replace stator.

1. Make sure lights are not burned out.

2. Disconnect the lighting lead (yellow) from the wiring harness.

Lights

With engine running in the fast seing,

measure voltage from lighting lead to ground using an AC voltmeter.

3. With engine stopped, measure the resistance of stator from lighting lead to ground using an ohmmeter.

If resistance is inﬁnity ohms, stator winding

or lead is open. Replace stator.

1. Replace burned out lights.

2. If voltage is 13 volts or more, stator is OK.

Check for loose connections or shorts in wiring harness.

If voltage is less than 13 volts, test stator

using an ohmmeter (Test 3).

3. If resistance is approximately 0.15 ohms,

stator is OK.

If resistance is 0 ohms, stator is shorted.

Replace stator.

If resistance is inﬁnity ohms, stator or

lighting lead is open. Replace stator.

7.9

Page 62

Section 7 Electrical System and Components

Troubleshooting Guide 3 amp/70 Watt Braking Stator (Continued)

Problem

Lights

Battery

Charging

(Braking

System

Test)

1. Make sure lights are not burned out.

2. Disconnect the braking lead (green) from the wiring harness.

With engine running in the fast seing,

measure voltage from braking lead to ground using an AC voltmeter.

3. With the engine stopped, measure the resistance from braking lead to ground using an ohmmeter.

Test

1. Replace burned out lights.

2. If voltage is 35 volts or more, stator

is OK. Circuitry on unit that grounds braking lead is shorted.

If voltage is less than 35 volts, test stator

using an ohmmeter (Test 3).

3. If resistance is approximately

0.2-0.4 ohms, stator is OK.

If resistance is 0 ohms, stator is shorted.

Replace stator.

If resistance is inﬁnity ohms, stator or

lighting lead is open. Replace stator.

Conclusion

7.10

Page 63

Battery Charging System 9 or 15 amp

Section 7

Electrical System and Components

Ground-to-Kill Lead

Key Switch

Optional Fuse

Battery

Starter Solenoid

White

Engine Connector

Optional Oil Sentry™ Indicator Light

Violet

Green

B+

RectiﬁerRegulator

Green

Stator

Flywheel

Ignition Module

Spark Plug

Red

Optional Fuel Solenoid

Optional Oil Sentry™ Switch (Shutdown)

Optional Oil Sentry™

Bendix Starter

Switch (Indicator)

Figure 7-9. Regulated Battery Charging System, 9 or 15 amp.

7.11

Page 64

Section 7 Electrical System and Components

Rectiﬁer-Regulator

Figure 7-10. 9 or 15 amp Stator and Rectiﬁer-Regulator.

DC Volt Meter

(-)

B+

9 or 15 Amp Stator

Rectiﬁer-Regulator

B+

Flywheel Stator

Battery

Figure 7-11. Proper Connection to Test 9 or 15 amp Charging System.

7.12

Ammeter

Page 65

Section 7

Electrical System and Components

Troubleshooting Guide 9 or 15 amp Regulated Battery Charging System

NOTE: Zero ohmmeters on each scale to ensure accurate readings. Voltage tests should be made with engine

running at full throle - no load. The baery must be fully charged.

Problem Test Conclusion

1. If voltage is 13.8-14.7 and charge rate increases when load is applied, the charging system is OK and baery was fully charged.

If voltage is less than 13.8 or charge rate does

not increase when load is applied, test stator (Tests 2 and 3).

2. If voltage is 28 volts or more, stator is OK. Rectiﬁer-regulator is probably faulty. Verify with Rectiﬁer-regulator tester KO3221.

If voltage is less than 28 volts, stator is probably

faulty and should be replaced. Test stator further using an ohmmeter (Test 3).

3a. If resistance is 0.1/0.2 ohms, the stator is OK.

If the resistance is inﬁnity ohms, stator is open.

Replace stator.

Charge

Battery

1. Trace B+ lead from rectiﬁer-regulator to key switch, or other accessible connection. Disconnect it from switch or connection. Connect an ammeter from loose end of B+ lead to positive terminal of baery. Connect DC voltmeter from loose end of B+ lead to negative terminal of baery. See Figure 7-11. With engine running in the fast position, read voltage on voltmeter.

If voltage is 13.8 volts or more, place a

minimum load of 5 amps* on baery to reduce voltage. Observe ammeter.

*NOTE: Turn on lights, if 60 was or more.

Or place a 2.5 ohm, 100 wa resistor across baery terminals.

2. Remove connector from rectiﬁer-regulator. With engine running in the fast position, measure AC voltage across stator leads using an AC voltmeter.

3a. With engine stopped, measure the resistance

across stator leads using an ohmmeter.

Battery

Continuously

Charges At

High Rate

3b. With the engine stopped, measure the

resistance from each stator lead to ground using an ohmmeter.

1. Perform same test as step 1 above.

3b. If the resistance is inﬁnity ohms (no continuity),

the stator is OK (not shorted to ground).

If resistance (or continuity) is measured, the

stator is shorted to ground. Replace stator.

1. If the voltage is 14.7 volts or less the charging

system is OK. The baery is unable to hold a charge. Service baery or replace as necessary.

If voltage is more than 14.7 volts, the rectiﬁer-regulator is faulty. Replace rectiﬁer-regulator.

7.13

Page 66

Section 7 Electrical System and Components

Blade Stop Stator Brake Circuit

The blade stop stator brake circuit is provided as a safety feature to ensure the application can meet ANSI (American National Standards Institute) application blade stop requirements.

The circuit is activated if the operator gets o of the seat of the application while mower blade system is activated or in certain reverse mow conditions.

The circuit is activated by taking the ignition shutdown (kill) lead to ground. This action turns on the stator-brake relay which shorts the charging AC stator leads to produce a magnetic eld that will counter or resist the rotation of the ywheel. This added resistance to rotation decreases the amount of time it takes for the application deck blades to come to a full stop.

As the Kohler blade stop stator brake circuit oen is operated in conjunction with other application circuits, the relay in the Kohler circuit is specially congured with a 680 ohm resistor in parallel with the relay coil. This is done to negate transient voltage signals that would be normally created by interrupting the relay current once the relay has been activated. Therefore, relay replacement must only be made with the properly identied relay.

12V Switched Power

Reverse Mow Module (OEM Supplied)

TRIAC

Stator Brake Relay Coil

Engine

PTO

90 Ω

Brake

680 Ω

Kill

Key Switch

CDI Ignition

Figure 7-12. Blade Stop Stator Brake Circuit Wiring Diagram.

7.14

Seat

Page 67

Stator Assembly

Wiring Harness

Stator leads to Rectiﬁer-Regulator

Electrical System and Components

Insert stator leads into connector slots shown either orientation is acceptable

Wiring Harness

Insert relay into harness connector as shown

Wire Tie (Black)

Center slot is empty

Position connector with relay approximately as shown and attach to starter with wire tie

Section 7

Push Wing Mount (Black)

Figure 7-13. Stator Brake and Relay Harness Connections.

Troubleshooting Stator Brake System

Problems that could occur with the Kohler portion circuit generally could be caused by two component failures or an incorrect relay replacement, which will create the following conditions:

Dead Battery The brake relay has failed and is keeping the stator shorted, so no charge current can be passed from the rectiﬁer-regulator to the baery, eventually allowing the baery to discharge.

Test

Check baery voltage using a test meter with the application oﬀ and then while the application is operating at maximum speed. The baery voltage should increase from the engine oﬀ condition to the engine full speed condition.

If it does not, shut down the engine, remove the relay from its socket and re-test at full engine speed.

If the baery voltage does not increase with the engine operating, the problem is likely not with the stator brake relay.

Engine will crank but will not start

The brake stator relay is interacting with the application safeties or the reverse mow electronics, preventing normal engine start up.

Test

Remove the brake relay from its socket and aempt to restart the engine. If the engine starts, it is likely that the relay is not correct for this application or the transient protection resistor has failed. Replace the relay with the correct component.

If the engine does not start, the problem may exist with the application reverse mow circuit, the application safeties or with the key switch keeping the ignition shutdown line tied to engine ground.

Remove the engine shutdown (kill) lead from the application wire harness and aempt to start the engine again.

If the engine still does not start, you may have a fuel or ignition problem.

Perform other test associated with the charging stator and rectiﬁer-regulator to further determine root cause.

7.15

Page 68

Section 7 Electrical System and Components

Electric Starters

These engines use inertia drive starting motors.

Operation

When power is applied to the starter, the armature rotates. As the armature rotates, the drive pinion moves out on the splined drive sha and into mesh with the ﬂywheel ring gear. When the pinion reaches the end of the drive sha, it rotates the ﬂywheel and cranks the engine.

When the engine starts, the ﬂywheel rotates faster than the starter armature and drive pinion. This moves the drive pinion out of mesh with the ring gear and into the retracted position. When power is removed from the starter, the armature stops rotating and the drive pinion is held in the retracted position by the anti-dri spring.

Starting Motor Precautions

NOTE: Do not crank the engine continuously for

more than 10 seconds at a time. If the engine does not start, allow a 60-second cool-down period between starting aempts. Failure to follow these guidelines can burn out the starter motor.

NOTE: If the engine develops suﬃcient speed to

disengage the inertia drive starter but does not keep running (a false start), the engine rotation must be allowed to come to a complete stop before aempting to restart the engine. If the starter is engaged while the

ﬂywheel is rotating, the starter pinion and ﬂywheel ring gear may clash, resulting in

damage to the starter.

NOTE: If the starter does not crank the engine, shut

oﬀ the starter immediately. Do not make further aempts to start the engine until the condition is corrected.

NOTE: Do not drop the starter or strike the starter

frame or end cap. Doing so can damage the starter.

Troubleshooting Guide - Starting Difﬁculties

Problem

Starter

Does Not

Energize

Starter Energizes But Turns

Slowly

Possible Fault Correction

Battery

Wiring

Starter Switch

or Solenoid

Battery

Brushes

Transmission

Engine

1. Check the speciﬁc gravity of baery. If low, recharge or replace baery as necessary.

1. Clean corroded connections and tighten loose connections.

2. Replace wires in poor condition.

1. Bypass the switch or solenoid with a jumper wire. If starter cranks normally, replace the faulty components.

1. Check the speciﬁc gravity of baery. If low, recharge or replace baery as necessary.

2. Baery too small, must be at least 250 cold-cranking amps.

1. Check for excessively dirty or worn brushes and commutator. Clean commutator using a coarse cloth (not emery cloth).

2. Replace brushes if excessively or unevenly worn.

1. Make sure the clutch or transmission is disengaged or placed in neutral. This is especially important on equipment with

hydrostatic drive. The transmission must be exactly in neutral to

prevent resistance which could keep the engine from starting.

2. Check for seized engine components such as the bearings, connecting rod, and piston.

7.16

Page 69

Starter Removal and Installation

Refer to the Disassembly and Reassembly Sections for starter removal and installation procedures.

Starter Drive Service

Every 500 hours of operation, clean and lubricate the splines on the starter drive sha. If the drive pinion is worn, or has chipped or broken teeth, it must be replaced. See Figure 7-14.

It is not necessary to completely disassemble the starter to service the drive components.

Section 7

Electrical System and Components

Figure 7-15. Assembling Inner Half of Tool Around The Armature Shaft and Retaining Ring.

Spring Retainer

Drive Nut (Collar)

Figure 7-14. Drive Components.

1. Disassemble the retaining ring, use tool (See Section 2).

2 Referring to Figure 7-14, grasp the spring retainer

and push it toward the starter, compressing the anti-dri spring and exposing the retaining ring.

3. Holding the spring retainer in the retracted position, assemble the inner halves of the removal tool around the armature sha with the retaining ring in the inner groove (see Figure 7-15). Slide the collar over the inner halves to hold them in position.

Retaining Ring

AntiDrift Spring

Drive Pinion

4. Thread the center screw into the removal tool until you feel resistance. Use a wrench (1 1/8" or adjustable) to hold the base of the removal tool. Use another wrench or socket (1/2" or 13 mm) to turn the center screw clockwise (see Figure 7-16). The resistance against the center screw will tell you when the retaining ring has popped out of the groove in the armature sha.

Figure 7-16. Holding Tool and Turning Center Screw (Clockwise) to Remove Retaining Ring.

5. Remove the drive components, and drive nut (collar) from the armature sha, paying aention to the sequence. If the splines are dirty, clean them with solvent.

6. The splines should have a light ﬁlm of lubricant. Relubricate as necessary with Kohler bendix starter lubricant (See Section 2). Reinstall or replace the drive components, assembling them in the same sequence as they were removed.

7.17

Page 70

Section 7 Electrical System and Components

Retaining Ring Installation

1. Position the retaining ring in the groove in one of the inner halves. Assemble the other half over the top and slide on the outer collar.

2. Be certain the drive components are installed in correct sequence onto the armature sha.

3. Slip the tool over the end of the armature sha, so the retaining ring inside is resting on the end of the sha. Hold the tool with one hand, exerting slight pressure toward the starter. Tap the top of the tool with a hammer until you feel the retaining ring snap into the groove. Disassemble and remove the tool.

4. Squeeze the retaining ring with pliers to compress it into the groove.

5. Assemble the inner halves with the larger cavity around the spring retainer (see Figure 7-17). Slide the collar over them and thread the center screw in until resistance is felt.

3. Remove the thru bolts and recessed hex nuts.

4. Remove the commutator end cap and li out the brush carrier assembly with the brushes and springs.

5. Remove the drive end cap, then pull the armature with the thrust washer and wave washer (as equipped) out of the starter frame.

Retaining Ring

Retainer

Anti-Drift Spring

Pinion

Drive Nut (Collar)

Hex Flange Nuts

Drive End Cap

Thrust Washer

Figure 7-17. Assembling Larger Inner Half Around Spring Retainer.

6. Hold the base of the tool with a 1 1/8" wrench and turn the center screw clockwise with a 1/2" or 13 mm wrench to draw the spring retainer up around the retaining ring. Stop turning when the resistance increases. Disassemble and remove the tool.

Starter Disassembly

1. Remove the drive components following the instructions for servicing the drive.

2. Remove the hex ﬂange nut and insulating washer from the positive (+) brush lead stud.

Wave Washer

Armature

Frame Assembly

Brush Carrier Assembly

Commutator End Cap

Insulating Washer

Hex Flange Nut

Thru Bolts

Figure 7-18. Inertia Drive Electric Starter.

7.18

Page 71

Section 7

Electrical System and Components

Brush Replacement

1. Remove the hex ﬂange nut and insulating washer from the positive (+) brush lead stud.

2. Remove the thru bolts and captured hex nuts.

3. Remove the commutator end cap, then pull the brush carrier assembly out of the frame. See

Figure 7-19.

Figure 7-19. Removing Brush Carrier Assembly.

Commutator Service

Clean the commutator with a coarse, lint free cloth. Do not use emery cloth.

If the commutator is badly worn or grooved, turn it down on a lathe or replace the armature.

2. Insert the armature into the starter frame. The magnets will hold it in place. See Figure 7-21.

Figure 7-21. Armature Installed in Starter Frame.

3. Align the holes with the spaces between the magnets and install the drive end cap onto the front of the frame.

4. If the brush assembly is not being replaced, position the springs and brushes within their pockets in the carrier; move them to the retracted position, and install carton staples to retain them. See Figure 7-22. Replacement brushes come pre-assembled in the carrier housing, retained with two carton staples.

Starter Reassembly

1. Place the wave washer, followed by the thrust washer onto the drive sha of the armature. See Figure 7-20.

Figure 7-20. Washers Installed on Armature.

Figure 7-22. Brush Carrier Assembly with Staples.

7.19

Page 72

Section 7 Electrical System and Components

5. Hold the brush holder assembly with the positive brush lead stud up. Align the molded sections with the corresponding cutouts in the starter frame and slide the brush carrier assembly into place. The commutator will push the carton staples out as the brush assembly is inserted. See Figure 7-23.

Figure 7-23. Installing Brush Carrier Using Staples.

6. Position the commutator end cap over the brush assembly, aligning the holes for the stud terminal and the thru bolts.

8. Install the insulating washer and hex ﬂange nut onto the positive (+) brush lead stud. Make sure the stud is centered and does not touch the metal end cap. Torque the hex ﬂange nut to 2.2-4.5 N·m (20-40 in. lb.).

NOTE: Aer installation and connection of the

starter lead, torque the outer nut to

1.6-2.8 N·m (12-25 in. lb.), do not over torque.

9. Lubricate the drive sha with Kohler bendix starter drive lubricant (See Section 2). Install the drive components following the instructions for servicing the drive. The completed starter is shown in Figure 7-25.

7. Install the thru bolts and hex nuts. Torque to

3.3-3.9 N·m. (30-35 in. lb.). See Figure 7-24.

Figure 7-24. Torquing Thru Bolts.

Figure 7-25. Assembled Starter.

7.20

Page 73

Disassembly

Section 8

Disassembly

WARNING: Accidental Starts!

Disabling engine. Accidental starting can cause severe injury or death. Before working on the engine or

equipment, disable the engine as follows: 1) Disconnect the spark plug lead. 2) Disconnect negative (-) baery cable from baery.

Section 8

The following sequence is suggested for complete engine disassembly. This procedure can be varied to accommodate options or special equipment.

Clean all parts thoroughly as the engine is disassembled. Only clean parts can be accurately inspected and gauged for wear or damage. There are many commercially available cleaners that will quickly remove grease, oil, and grime from engine parts. When such a cleaner is used, follow the manufacturer’s instructions and safety precautions carefully.

Make sure all traces of the cleaner are removed before the engine is reassembled and placed into operation. Even small amounts of these cleaners can quickly break down the lubricating properties of engine oil.

Typical Disassembly Sequence

1. Drain oil from the crankcase and remove oil ﬁlter.

2. Remove blower housing.

3. Disconnect spark plug lead.

4. Remove muﬄer.

5. Remove rectiﬁer-regulator.

6. Remove electric starter.

7. Remove air cleaner.

8. Remove external governor components, carburetor and fuel pump.

9. Remove ignition module.

10. Remove grass screen, fan, and ﬂywheel.

11. Remove stator.

12. Remove valve cover and cylinder head.

13. Remove closure plate and wiring harness.

14. Remove cam gears, cam shas, and oil pump.

15. Remove connecting rod and piston.

16. Remove piston from connecting rod.

17. Remove piston rings.

18. Remove cranksha and balance weight assembly.

19. Remove balance weight assembly from

cranksha.

20 Remove governor cross sha.

21. Remove PTO and ﬂywheel side oil seals.

Drain Oil from Crankcase and Remove Oil Filter

1. Remove the oil drain plug and oil ﬁll cap/ dipstick. See Figure 8-1.

2. Allow ample time for the oil to drain from the crankcase.

3. Remove and discard the oil ﬁlter.

Oil Fill Cap/ Dipstick

Oil Filter

Oil Drain Plug

Figure 8-1. Oil Drain Location, Oil Filter, and Oil Fill Cap/Dipstick.

8.1

Page 74

Section 8 Disassembly

Remove Oil Sentry™ Pressure Switch (On Models So Equipped)

1. Disconnect the lead from the Oil Sentry™ pressure switch.

2. Remove the pressure switch from the center passage or adapter elbow in the closure plate. See

Figure 8-2.

Figure 8-2. Removing Oil Sentry™ Switch.

Remove Mufﬂer

1. Remove the hex ﬂange nuts or 5/16-18 capscrews aaching the muﬄer or exhaust system to the engine. Remove any aached brackets. See Figure 8-4.

2. Remove the muﬄer and gasket from the exhaust

port.

Figure 8-4. Removing Exhaust Flange Nuts (Stud Design).

Remove Blower Housing

1. Remove the four shoulder screws securing the blower housing to the closure plate. See Figure

8-3.

2. Li the blower housing and separate the spark

plug lead from the corresponding slot.

Figure 8-3. Removing Blower Housing Screws.

Disconnect Spark Plug Lead

1. Carefully pull on the boot section and disconnect the spark plug lead.

Remove Rectiﬁer-Regulator

1. Unplug the connector from the rectiﬁer-regulator.

2. Remove the two screws securing the rectiﬁerregulator to the crankcase. Remove the rectiﬁerregulator. See Figure 8-5.

Figure 8-5. Removing Rectiﬁer-Regulator.

Remove Electric Starter

1. Disconnect the starter lead from the terminal stud.

2. Remove the two hex ﬂange nuts securing the

starter to the closure plate. Remove the starter.

See Figure 8-6.

8.2

Page 75

Figure 8-6. Removing Electric Starter.

Remove Air Cleaner

1. Loosen the two knobs and remove the air cleaner

cover. See Figure 8-7.

Section 8

Disassembly

3. Remove the two hex ﬂange nuts, or single nut

and long mounting screw securing the air cleaner

base. See Figure 8-9.

Figure 8-9. Removing Air Cleaner Base Fasteners.

4. Disconnect the breather hose from the valve cover and remove the air cleaner base and gasket.

See Figure 8-10.

Figure 8-7. Removing Air Cleaner Cover.

2. Remove the precleaner (if so equipped), and the air cleaner element with the formed rubber seal.

See Figure 8-8.

Figure 8-8. Air Cleaner Components.

Figure 8-10. Removing Air Cleaner Base and Breather Hose.

Remove External Governor Components, Carburetor, and Fuel Pump

WARNING: Explosive Fuel!

running, since spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Do not start the engine near spilled fuel. Never use gasoline as a cleaning agent.

8.3

Page 76

Section 8 Disassembly

1. Shut oﬀ the fuel supply. Disconnect the fuel line from the carburetor inlet ﬁing. See Figure 8-11.

If a fuel pump is used, disconnect the pulse line

from the ﬁing on the closure plate. See Figure 8-12.

Figure 8-11. Disconnecting Fuel Line from Carburetor.

Figure 8-13. Removing Heat Deﬂector Screw and

Ground Lead.

3. If the carburetor uses a fuel solenoid, carefully cut the plastic tie strap and disconnect the fuel solenoid lead from the wiring harness. See Figure

8-14.

Figure 8-12. Disconnecting Pulse Line from Fitting.

2. Remove the heat deﬂector mounting screw and

special washer, which also secures the ground

lead for the fuel shut-oﬀ solenoid, if so equipped. See Figure 8-13.

8.4

Figure 8-14. Disconnecting Fuel Solenoid Lead.

4. Slide the carburetor outward and disconnect the

throle and choke linkages. See Figure 8-15.

Figure 8-15. Removing Carburetor.

Page 77

5. Mark the mounted position of the speed control

bracket in the sloed holes and remove the two

screws securing the speed control bracket to the closure plate. Note or mark the governor spring hole for correct installation later. Unhook the governor spring, then remove the control bracket

(with fuel pump aached, if equipped) and linkages from the engine. See Figures 8-16 and 8-17.

Figure 8-16. Removing Speed Control Bracket from Closure Plate.

Section 8

Disassembly

Figure 8-18. Removing Governor Lever.

7. Remove the carburetor gasket, then carefully

remove the heat deﬂector and gasket from the intake stud. The heat deﬂector is made from a plastic that is quite brile. Do not pry on the corners, or you risk cracking/breaking the deﬂector. If prying is necessary to loosen the deﬂector, carefully pry near the intake stud only. See Figure 8-19. Remove the mounting stud from

the cylinder only if required.

Figure 8-17. Disconnecting Governor Spring.

6. Loosen the hex ﬂange nut and remove the governor lever* from the governor cross sha. See Figure 8-18.

*NOTE: It is recommended that a new governor lever

be installed whenever removal is performed.

Figure 8-19. Removing Heat Deﬂector.

8.5

Page 78

Section 8 Disassembly

8. Remove the insert from the intake port (some

models), if separate from the heat deﬂector. See Figure 8-20.

Insert

Figure 8-20. Removing Insert (Some Models).

Remove Ignition Module

1. Disconnect the kill lead from the ignition module.

2. Rotate the ﬂywheel magnet away from the

module.

3. Remove the RFI sheathed spark plug lead with from retaining clip, if so equipped. See Figure

8-21.

Figure 8-22. Removing Ignition Module.

Remove Grass Screen, Fan, and Flywheel

1. Unsnap the grass screen from the cooling fan. See

Figure 8-23.

Figure 8-23. Removing Grass Screen.

NOTE: Always use a ﬂywheel strap wrench or

ﬂywheel holding tool (see Section 2) to hold

the ﬂywheel when loosening or tightening the ﬂywheel and fan retaining fasteners. Do

not use any type of bar or wedge between

the ﬁns of the cooling fan, as the ﬁns could

become cracked or damaged.

Figure 8-21. Removing Lead from Clip (RFI Suppression Equipped Units.

4. Remove the two hex ﬂange screws and the ignition module. See Figure 8-22.

8.6

2. Remove the retaining screw, washer and the fan

mounting plate, securing the fan and ﬂywheel to the cranksha. See Figure 8-24.

Page 79

Section 8

Disassembly

Figure 8-24. Removing Fan and Flywheel Mounting Hardware.

3. Carefully li the cooling fan to disengage the two drive pins and remove it from the ﬂywheel.

4. Remove the ﬂywheel from the cranksha using a puller. See Figure 8-25.

NOTE: Always use a puller to remove the

ﬂywheel from the cranksha. Do not strike the cranksha or ﬂywheel, as they

could be cracked or damaged.

Figure 8-26. Removing Stator.

Remove the Valve Cover and Cylinder Head

1. Remove the seven screws securing the valve cover

and any aached brackets. See Figure 8-27.

Figure 8-27. Removing Valve Cover Screws.

2. Remove the valve cover and gasket from the

cylinder head. See Figure 8-28.

Figure 8-25. Removing Flywheel Using Puller.

5. Remove the ﬂywheel key from the crank sha.

Remove the Stator

1. Remove the two screws securing the stator to the

closure plate bosses. See Figure 8-26.

NOTE: To disconnect the B+ or stator leads from

the wiring harness connector, insert a

small screwdriver, or similar narrow ﬂat

blade, and bend down the locking tang of the terminal(s). Gently pull the lead(s) out of the connector.

Figure 8-28. Valve Cover and Gasket Details.

8.7

Page 80

Section 8 Disassembly

3. Loosen the inner set screws (T15 TORX) and

back oﬀ the rocker arm adjusting nuts. Remove

the push rods and mark them, so they can be

reinstalled in the same location. See Figure 8-29.

Figure 8-29. Loosening Adjustment Set Screw and Nut.

Figure 8-31. Removing Cylinder Head and Gasket.

6. Remove the drain back check ball (some models) from the keyhole slot in the crankcase. See Figure

8-32. Models without a check ball have an

internal drain back tube in the crankcase.

4. Remove the six hex ﬂange screws securing the

cylinder head. Note the thick washer used on the screw closest to the exhaust port. See Figure

8-30.

Washer

Figure 8-30. Removing Cylinder Head Bolts and Washer.

5. Remove the cylinder head and head gasket. See

Figure 8-31.

Figure 8-32. Removing Drain Back Check Ball from Crankcase (Some Models).

8.8

Page 81

Disassemble Cylinder Head

NOTE: Before disassembly, mark all valve train

components that will be reused, to assure they are reassembled on the same side.

1. Remove the spark plug. See Figure 8-33.

Section 8

Disassembly

Figure 8-35. Removing Valves with Spring Compressor.

Figure 8-33. Removing Spark Plug.

2. Remove the adjustment nuts, pivots and rocker

arms from the pivot studs.

3. Remove the rocker arm pivot studs and push rod

guide plates. See Figure 8-34.

Figure 8-34. Disassembling Rocker Arm Components.

4. Remove the valves.

a. Compress the valve springs using a valve

spring compressor and remove the keepers.

See Figure 8-35.

Remove Closure Plate

1. Remove the fourteen hex ﬂange screws securing

the closure plate to the crankcase. See Figure

8-36. Note the location and position of any

aached clips or clamps.

Figure 8-36. Removing Closure Plate Screws.

2. A gasket is used between the closure plate and crankcase. If necessary, carefully tap on the

bosses for the starter or oil ﬁlter with a so-

faced mallet to loosen. Do not pry on the gasket surfaces of the crankcase or oil pan, as this can cause damage resulting in leaks.

b. Remove the compressor; then remove the

valve spring caps, valve springs, and valves.

8.9

Page 82

Section 8 Disassembly

3. Remove the closure plate assembly and gasket.

See Figure 8-37.

4. If the wiring harness needs to be separated from the closure plate, pry open the clamps and pull out through the slot.

Figure 8-37. Closure Plate and Gasket Removed from Crankcase.

Disassemble Closure Plate

1. Remove the governor gear and regulating pin assembly. Gently pry upward using the blades of

two small screwdrivers. See Figure 8-38.

NOTE: The governor gear is held onto the sha by

small molded tabs in the gear. When the gear is removed these tabs are destroyed and the gear must be replaced. Governor gear removal is required for closure plate disassembly and cleaning of the oil passages.

2. Remove the six screws securing the oil passage cover to the closure plate. Remove the cover and

gasket. See Figure 8-39.

Figure 8-39. Removing Oil Passage Cover and Gasket.

Remove Cam Gears, Cam Shafts, and Oil Pump

1. Remove the thrust washer(s) and cam gears from

the cam shas. Later models will have a thrust washer on the exhaust side only. See Figure 8-40.

NOTE: The ACR weight and spring normally

captured by the thrust washer and installation of closure plate, will fall out if the exhaust cam gear is turned upside down.

Thrust Washer (Intake Side) Early Models Only

Figure 8-38. Removing Governor Gear.

8.10

Figure 8-40. Removing Cam Gears.

Page 83

2. Remove the screws securing the cam levers to the

crankcase. See Figure 8-41. Mark the cam levers

for proper reassembly.

NOTE: Cam Gear assemblies may contain either two

or four rivets. The four rivet design is shown

in ﬁgures.

Figure 8-41. Removing Cam Levers.

3. Pull the exhaust side cam sha and sloed thrust washer, out of the crankcase. See Figure 8-42.

Section 8

Disassembly

Drain Back Tube

Figure 8-43. Removing Drain Back Tube (Some Models).

NOTE: Engine Serial No. 332740003 and Lower, use

a rubber outlet between the oil pump outlet and lower main bearing area. Some models use an open seal with an internal passage to feed oil to the lower bearing. Some models use a closed or solid seal, and the cranksha

is crossed-drilled to feed oil to the lower bearing. See Figure 8-44.

Engine Serial No. 332740003 and Higher, the

outlet of the oil pump is closed and no rubber

seal is used. See Figure 8-45.

Figure 8-42. Removing Exhaust Side Cam Shaft and Slotted Thrust Washer.

4. If the engine contains an internal drain back tube, unhook it from the oil pump and pull it out of the crankcase passage. Check for cracks,

brileness or damage. Replace if questionable in any way. See Figure 8-43.

Open Seal Closed Seal

Figure 8-44. Outlet Seal Styles (Some Models).

Open Outlet Style (Requires Seal)

Figure 8-45. Pump Outlet Styles.

Closed Outlet Style

8.11

Page 84

Section 8 Disassembly

5. Remove the two screws securing the oil pump

and intake side cam sha to the crankcase. If

a drain back tube is used, it may be unhooked and removed separately or together with oil

pump. Carefully pull upward on the cam sha to

remove the assembly from the crankcase cavity. A small rubber oil pump outlet seal on the outlet of the oil pump may become dislodged during removal. Do not lose it. See Figures 8-44 and 8-46.

Outlet Seal (Some Models)

Figure 8-46. Intake Cam Shaft and Oil Pump Assembly.

6. If necessary, the oil pump can be separated from the intake side cam sha. Provide appropriate

support for the sha, and drive out the lower

pin. The oil pump assembly can then be removed from the cam sha. See Figure 8-47.

Remove Connecting Rod and Piston

1. Rotate the cranksha so the rod journal is in the 9 o’clock position.

NOTE: If a carbon ridge is present at the top of the

bore, use a ridge reamer to remove it before

aempting to remove the piston.

2. Remove the two hex ﬂange screws and the connecting rod cap. See Figures 8-48.

Figure 8-48. Removing Connecting Rod Cap.

3. Carefully push the connecting rod and the piston

away from the cranksha and out of the cylinder bore. See Figure 8-49.

Figure 8-47. Separating Oil Pump Assembly from Intake Side Cam Shaft.

8.12

Figure 8-49. Removing Piston and Connecting Rod.

Page 85

Section 8

Disassembly

Remove Piston from Connecting Rod

1. Remove the wrist pin retainer and wrist pin. Separate the piston from the connecting rod. See

Figure 8-50.

Figure 8-50. Separating Piston from Connecting Rod.

Remove Piston Rings

1. Remove the top and center compression rings using a ring expander. See Figure 8-51.

Remove Crankshaft and Balance Weight Assembly

1. Carefully remove the cranksha and balance weight assembly from the crankcase. See Figure

8-52. On engines aer Serial No. 3618005223, carefully li the lower control link (for balance weight), oﬀ the boss of crankcase as the cranksha is removed. See Figure 8-53.

Figure 8-52. Removing Crankshaft and Balance Weight Assembly (Before Serial No. 3618005213).

2. Remove the oil control ring rails, then remove the spacer.

Figure 8-51. Removing Piston Rings.

Figure 8-53. Removing Crankshaft and Link (After Serial No. 3618005223).

8.13

Page 86

Section 8 Disassembly

Balance Weight Disassembly

If necessary, the balance weight assembly can be

separated from the cranksha. Disassemble only if

required.

1. Remove the crank gear from the cranksha and

carefully remove the key from the keyway. See

Figure 8-54.

Figure 8-55. Removing Balance Weight Screw (Guide Shoe Design Before Serial No. 3618005213).

Figure 8-54. Removing Crank Gear Key.

2. Remove the guide shoe from the guide pin on

the ﬂywheel side of the assembly (Before Serial No. 3618005213). See Figure 8-55. Remove the

link from the guide pin on the PTO side of the assembly (Aer Serial No. 3618005223). See

Figure 8-56.

3. Remove the long hex ﬂange screw securing

the two balance weight halves together on the

cranksha. Note the orientation of all parts. The guide pin is on ﬂywheel side for the balance

weight design with the closure plate side guide shoe. The guide pin is on PTO side for the balance weight design with the lower control link. Hold the guide pin with wrench or torx bit socket as required. Do not hold or damage the outside diameter (O.D.) of the guide pin. See

Figure 8-55 or 8-56.

Figure 8-56. Removing Balance Weight Screw and Guide Pin (Control Link Design After Serial No.

3618005223).

8.14

Page 87

4. Mark the weights for proper reassembly and

carefully slide the balance weights oﬀ the cranksha eccentrics. See Figures 8-57 and 8-58.

Figure 8-57. Disassembled Balance Weight (Guide Shoe Design Before Serial No. 3618005213).

Section 8

Disassembly

Figure 8-59. Removing Hitch Pin and Washer.

2. Slide the sha inward and remove it through the

inside of the crankcase. Be careful not to lose the

small washer in the inside portion of the sha. See Figure 8-60.

Figure 8-58. Disassembled Balance Weight (Control Link Design After Serial No. 3618005223).

Remove Governor Cross Shaft

1. Remove the hitch pin and washer located on the

outside of the governor cross sha. See Figure 8-59.

Figure 8-60. Removing Governor Cross Shaft.

Remove PTO and Flywheel Side Oil Seals

1. Use a seal puller to remove the PTO and ﬂywheel side oil seals. See Figure 8-61.

Figure 8-61. Removing Seal with a Seal Puller.

8.15

Page 88

Section 8 Disassembly

8.16

Page 89

Section 9

Inspection and Reconditioning

Section 9

Inspection and Reconditioning

This section covers the operation, inspection, and repair/reconditioning of major internal engine components. The following components are not covered in this section. They are covered in sections of their own:

Air Cleaner, Section 4 Carburetor and External Governor, Section 5 Ignition, Charging and Electric Starter, Section 7

Clean all parts thoroughly. Only clean parts can be accurately inspected and gauged for wear or damage. There are many commercially available cleaners that will quickly remove grease, oil, and grime from engine parts. When such a cleaner is used, follow the manufacturer’s instructions and safety precautions carefully. Use gasket remover to remove old material from the valve cover, cylinder head, crankcase, and oil pan. Do not scrape the gasket surfaces, as this could cause damage that results in leaks.

Make sure all traces of cleaning solvents are removed before the engine is reassembled and placed into operation. Even small amounts of these cleaners can quickly break down the lubricating properties of engine oil.

Refer to A Guide to Engine Rebuilding (TP-2150) for additional information. Measurement Guide (TP-2159-A) and Engine Inspection Data Record (TP-2435) are also available; use these to record inspection results.

Automatic Compression Release (ACR)

This engine is equipped with an Automatic Compression Release (ACR) mechanism. The ACR lowers compression at cranking speeds to make starting easier.

Operation

The ACR mechanism consists of an actuating spring

and a pivoting ﬂyweight/control pin assembly,

located in the exhaust side cam gear. A thrust washer and mounting of the closure plate hold the ACR in position. See Figure 9-1. At cranking speeds (700 RPM

or lower), the spring holds the ﬂyweight in and the

rounded surface of the control pin protrudes above the exhaust cam lobe. This pushes the exhaust valve

oﬀ its seat during the ﬁrst part of the compression stroke. The compression is reduced to an eﬀective

ratio of about 2:1 during cranking.

When the engine is stopped, the spring returns the

ﬂyweight/control pin assembly to the compression

release position, ready for the next start.

Control Pin Lower Section

Cam Lobe

Flyweight

Cam Gear

Spring

Aer starting, when engine speed exceeds 700 RPM, centrifugal force overcomes the force of the ﬂyweight spring. The ﬂyweight moves outward, rotating the control pin to expose the ﬂat surface, which is lower

than the cam lobe. The control pin no longer has any

eﬀect on the exhaust valve, and the engine operates at

full power.

Thrust Washer

Figure 9-1. ACR Details.

9.1

Page 90

Section 9 Inspection and Reconditioning

Beneﬁts

Reducing the compression at cranking speeds results

in several important beneﬁts.

1. The starter and baery can be smaller, more

practical for the applications in which these engines are used.

2. ACR eliminates kickback during starting, so a spark retard/advance mechanism is no longer required.

3. The choke control seing is less critical with ACR. In the event of ﬂooding, excess fuel is blown out

the opened exhaust valve and does not hamper starting.

4. Engines with ACR start much faster in cold weather.

5. Engines with ACR can be started with spark plugs that are worn or fouled. Engines without ACR would be less likely to start with the same plugs.

Cam Gears

Inspection and Service

Inspect the gear teeth and cam lobes of the intake and exhaust cam gears. If the lobes exhibit excessive wear, or the teeth are worn, chipped or broken, replacement of the cam gear(s) will be necessary.

Crankshaft and Crank Gear

Inspection and Service

Inspect the teeth of the crank gear. If the teeth are badly worn, chipped, or some are missing, replacement of the crank gear will be necessary.

Remove the gear by pulling it oﬀ the key and cranksha.

Inspect the cranksha bearing journal surfaces for

wear, scoring, grooving, etc. If they show signs of

damage or are out of running clearance speciﬁcations, the cranksha must be replaced.

Inspect the cranksha keyways. If worn or chipped, replacement of the cranksha will be necessary.

Inspect the crankpin for wear, score marks or aluminum transfer. Slight score marks can be cleaned with crocus cloth soaked in oil. If wear limits are exceeded (see Section 1), it will be necessary to replace

the cranksha.

Crankcase

Inspection and Service

Check all gasket surfaces to make sure they are free of gasket fragments and deep scratches or nicks.

Check the cylinder wall for scoring. In severe cases, unburned fuel can wash the necessary lubricating

oil oﬀ the piston and cylinder wall. The piston rings

make metal to metal contact with the wall, causing

scuﬃng and scoring. Scoring of the cylinder wall can

also be caused by localized hot spots from blocked

cooling ﬁns or from inadequate or contaminated

lubrication.

If the cylinder bore is scored, worn, tapered, or outof-round, resizing may be possible. Use an inside micrometer or telescoping gauge to determine the amount of wear (refer to Section 1). If wear exceeds the published limits, a 0.08 mm (0.003 in.) oversize piston is available. If the cylinder will not clean up at 0.08 mm (0.003 in.) oversize, a short block or replacement engine will need to be considered.

Honing

While most commercially available cylinder hones can be used with either portable drills or drill presses, the use of a low speed drill press is preferred as it facilitates more accurate alignment of the bore in

relation to the cranksha counter bore. Honing is best

accomplished at a drill speed of about 250 RPM and 60 strokes per minute. Aer installing coarse stones in

hone, proceed as follows:

1. Lower the hone into the bore and, aer centering,

adjust it so that the stones are in contact with

the cylinder wall. Use of a commercial cuing-

cooling agent is recommended.

2. With the lower edge of each stone positioned even with the lowest edge of the bore, start the drill and honing process. Move the hone up and down while resizing to prevent the formation of

cuing ridges. Check the size frequently. Make

sure the bore is cool when measuring.

9.2

Page 91

Section 9

Inspection and Reconditioning

3. When the bore is within 0.064 mm (0.0025 in.)

of desired size, remove the coarse stones and replace with burnishing stones. Continue with the burnishing stones until within 0.013 mm

(0.0005 in.) of desired size and then use ﬁnish

stones (220-280 grit) and polish to ﬁnal size. A

crosshatch should be observed if honing is done correctly. The crosshatch should intersect at

approximately 23-33° oﬀ the horizontal. Too ﬂat

an angle could cause the rings to skip and wear excessively, too steep an angle will result in high oil consumption (refer to Figure 9-2).

Measuring Piston-to-Bore Clearance

Before installing the piston into the cylinder bore, it is necessary that the clearance be accurately checked.

This step is oen overlooked, and if the clearances are not within speciﬁcations, engine failure will usually

result.

NOTE: Do not use a feeler gauge to measure piston-

to-bore clearance – it will yield inaccurate measurements. Always use a micrometer.

Use the following procedure to accurately measure the piston-to-bore clearance:

1. Use a micrometer and measure the diameter of

the piston perpendicular to the piston pin, up

8 mm (0.314 in.) from the boom of the piston

skirt as indicated in Figure 9-3.

Measure 8 mm (0.314 in.) Above the Bottom of Piston Skirt at Right Angles to Piston Pin.

Figure 9-2. Cylinder Bore Crosshatch after Honing.

4. Aer honing, check the bore for roundness, taper,

and size. Use an inside micrometer, telescoping gauge, or bore gauge to take measurements. The measurements should be taken at three locations in the cylinder – at the top, middle,

and boom. Two measurements should be taken

(perpendicular to each other) at each of the three locations.

Clean Cylinder Bore after Honing

Proper cleaning of the cylinder walls following honing

is critical. Grit le in the cylinder bore can destroy an engine in less than one hour of operation aer a

rebuild.

The ﬁnal cleaning operation should always be a

thorough scrubbing with a brush and hot, soapy water. Use a strong detergent that is capable of breaking down the machining oil while maintaining a good level of suds. If the suds break down during cleaning, discard the dirty water and start again with more hot water and detergent. Following the scrubbing, rinse the cylinder with very hot, clear water, dry it completely, and apply a light coating of engine oil to prevent rusting.

8 mm (0.314 in.)

Figure 9-3. Measuring Piston Diameter.

2. Use an inside micrometer, telescoping gauge, or bore gauge and measure the cylinder bore. Take the measurement approximately 63.5 mm (2.5 in.) below the top of the bore and perpendicular to the piston pin.

3. Piston-to-bore clearance is the piston diameter subtracted from the bore diameter (step 2 minus step 1).

Balance Weight Assembly

The balance weight assembly counterbalances

the cranksha weights and internal forces during

operation to minimize vibration. Several key areas of the balance weight must be checked before installation and use. Additionally, the mating components

(cranksha eccentrics and closure plate guide channel)

must also be inspected for wear or damage.

Use the following procedure to check the balance weight and matching components.

9.3

Page 92

Section 9 Inspection and Reconditioning

Balance Weight-to-Eccentric Clearance

Before the balance weight assembly is reassembled to

the cranksha, the running clearance to the cranksha

eccentrics must be accurately checked. Failure to maintain the required clearances will result in vibration or engine failure.

NOTE: Do not use a feeler gauge to measure balance

weight-to-eccentric clearance.

Measuring Balance Weight to Crankshaft Eccentric Ring(s) Clearance

1. Use an inside micrometer, telescoping gauge, or bore gauge and measure the inside diameter of the balance weight bearing surface. Take two measurements 90° to each other on each weight. See Figure 9-4.

3. The running clearance is the eccentric diameter subtracted from the balance weight bearing diameter (step 1 minus step 2). If the measurements are outside the maximum

wear limits listed in Section 1, the aﬀected

component(s) must be replaced.

Measuring Balance Weight Guide Pin and Guide Shoe-to-Closure Plate Guide Channel Running Clearance

1. Use an outside micrometer and measure the outside width of the balance weight guide shoe. See Figure 9-6.

Figure 9-4. Measuring Balance Weight Bearing Surface.

2. Then use an outside micrometer and measure

across each eccentric on the cranksha. Again

take two measurements 90° to each other. See Figure 9-5.

Figure 9-6. Measuring Balance Weight Guide Shoe.

2. Use an inside micrometer, telescoping gauge or similar tool and measure the width of the guide channel in the closure plate. See Figure 9-7. Record these dimensions.

Figure 9-7. Measuring Guide Channel in Closure Plate.

Figure 9-5. Measuring Crankshaft Eccentric.

9.4

Page 93

Section 9

Inspection and Reconditioning

3. Use an outside micrometer again and measure the O.D. of the balance weight guide pin. See Figure 9-8.

Figure 9-8. Measuring Guide Pin O.D.

4. Use a split ball gauge or dial calipers and measure the I.D. of the corresponding hole in the guide shoe. See Figure 9-9. Record these dimensions.

Flywheel

Inspection

Inspect the ﬂywheel for cracks and check the keyway for wear or damage. Replace the ﬂywheel if cracked. If the ﬂywheel key is sheared or the keyway is damaged, replace the cranksha, ﬂywheel, and key.

Inspect the ring gear for cracks or damage. Ring gears

are not available separately. Replace the ﬂywheel if the

ring gear is damaged.

Figure 9-9. Measuring Guide Shoe Hole I.D.

If any of the measurements taken are outside the

maximum wear limits listed in Section 1, the aﬀected

component(s) must be replaced.

9.5

Page 94

Section 9 Inspection and Reconditioning

Cylinder Head and Valves

Inspection and Service

Carefully inspect the valve mechanism parts. Inspect the valve springs and related hardware for excessive wear

or distortion. Check the valves and valve seats for evidence of deep piing, cracks, or distortion. Check the running clearance between the valve stems and guides. See Figure 9-10 for valve details and speciﬁcations.

Exhaust Valve

Intake Valve

A B C D E F G

Figure 9-10. Valve Details.

9.6

Seat Angle Guide Depth Guide I.D.

Valve Head Diameter

Valve Face Angle Valve Margin (Min.) Valve Stem Diameter

Dimension

Intake Exhaust

89°

10.20 mm

6.038/6.058 mm

37.625/37.375 mm 45°

1.5 mm

5.982/6.000 mm

89°

6.2 mm

6.038/6.058 mm

32.125/32.375 mm 45°

1.5 mm

5.970/5.988 mm

Page 95

Section 9

Inspection and Reconditioning

Hard starting, or loss of power accompanied by high fuel consumption, may be symptoms of faulty valves. Although these symptoms could also be aributed to worn rings, remove and check the valves ﬁrst. Aer

removal, clean the valve heads, faces, and stems with a power wire brush. Then, carefully inspect each valve for defects such as warped head, excessive corrosion, or worn stem end. Replace valves found to be in bad condition. A normal valve and valves in bad condition are shown in the accompanying illustrations.

Normal: Even aer long hours of operation a valve

can be reconditioned and reused if the face and margin are in good shape. If a valve is worn to where the margin is less than 1/32" do not reuse it. The valve shown was in operation for almost 1000 hours under controlled test conditions.

Bad Condition: The valve depicted here should be replaced. Note the warped head; margin damaged

and too narrow. These conditions could be aributed

to excessive hours or a combination of poor operating conditions.

Leakage: A poor grind on a valve face or seat will allow leakage, resulting in a valve burned on one side only.

Coking: Coking is normal on intake valves and is not harmful. If the seat is good, the valve could be reused

aer cleaning.

9.7

Page 96

Section 9 Inspection and Reconditioning

Excessive Combustion Temperatures: The white deposits seen here indicate very high combustion temperatures, usually due to a lean fuel mixture.

Stem Corrosion: Moisture in fuel or from condensation are the most common causes of valve stem corrosion. Condensation occurs from improper preservation during storage and when engine is repeatedly stopped before it has a chance to reach normal operating temperatures. Replace corroded valves.

Gum: Gum deposits usually result from using stale

gasoline. This condition is oen noted in applications where fuel is not drained out of tank during the oﬀ

season. Gum is a prevalent cause of valve sticking. The cure is to ream the valve guides and clean or replace the valves, depending on their condition.

9.8

Overheating: An exhaust valve subject to overheating will have a dark discoloration in the area above the valve guide. Worn guides and faulty valve springs may cause this condition. Also check for clogged air

intake, and blocked ﬁns when this condition is noted.

Page 97

Valve Guides

If a valve guide is worn beyond speciﬁcations, it will

not guide the valve in a straight line. This may result in burned valve faces or seats, loss of compression, and excessive oil consumption.

To check valve guide-to-valve stem clearance, thoroughly clean the valve guide and, using a splitball gauge, measure the inside diameter. Then, using an outside micrometer, measure the diameter of the valve stem at several points on the stem where it moves in the valve guide. Use the largest stem diameter to calculate the clearance. If the intake clearance exceeds 0.038/0.076 mm (0.0015/0.0030 in.) or the exhaust clearance exceeds 0.050/0.088 mm (0.0020/0.0035 in.), determine whether the valve stem or guide is responsible for the excessive clearance.

Maximum (I.D.) wear on the intake valve guide is

6.135 mm (0.2415 in.) while 6.160 mm (0.2425 in.)

is the maximum allowed on the exhaust guide. The guides are not removable. If the guides are within limits but the valve stems are worn beyond limits, replace the valves.

Valve Seat Inserts

Hardened steel alloy intake and exhaust valve seat inserts are press ﬁed into the cylinder head.

The inserts are not replaceable, but they can be

reconditioned if not too badly pied or distorted. If

the seats are cracked or badly warped, the cylinder head should be replaced.

Recondition the valve seat inserts following the

instructions provided with the valve seat cuer being used. A typical cuer is shown in Figure 9-11. The ﬁnal cut should be made with an 89° cuer as speciﬁed for

the valve seat angle in Figure 9-10. With the proper 45° valve face angle, and the valve seat cut properly (44.5° as measured from centerline when cut 89°) this would result in the desired 0.5° (1.0° full cut) interference angle where the maximum pressure occurs on the valve face and seat.

Section 9

Inspection and Reconditioning

Valve Seat Cutter

Pilot

Figure 9-11. Typical Valve Seat Cutter.

Lapping Valves

Reground or new valves must be lapped in, to provide a good seal. Use a hand valve grinder with suction

cup for ﬁnal lapping. Lightly coat valve face with ﬁne

grade of grinding compound, then rotate valve on seat with grinder. Continue grinding until smooth surface is obtained on seat and on valve face. Thoroughly clean cylinder head in soap and hot water to remove

all traces of grinding compound. Aer drying cylinder

head, apply a light coating of engine oil to prevent rusting.

Pistons and Rings

Inspection

Scuﬃng and scoring of pistons and cylinder walls

occurs when internal temperatures approach the welding point of the piston. Temperatures high enough to do this are created by friction, which is

usually aributed to improper lubrication, and/or

overheating of the engine.

Normally, very lile wear takes place in the piston

boss-piston pin area. If the original piston and

connecting rod can be reused aer new rings are

installed, the original pin can also be reused, but new piston pin retainers are required. The piston pin is part of the piston assembly; if the pin boss or the pin are worn or damaged, a new piston assembly is required.

Ring failure is usually indicated by excessive oil consumption and blue exhaust smoke. When rings fail, oil is allowed to enter the combustion chamber

where it is burned along with the fuel. High oil

consumption can also occur when the piston ring end gap is incorrect because the ring cannot properly conform to the cylinder wall under this condition. Oil control is also lost when ring gaps are not staggered during installation.

9.9

Page 98

Section 9 Inspection and Reconditioning

When cylinder temperatures get too high, lacquer and varnish collect on pistons causing rings to stick which results in rapid wear. A worn ring usually takes on a shiny or bright appearance.

Scratches on rings and pistons are caused by abrasive material such as carbon, dirt, or pieces of hard metal.

Detonation damage occurs when a portion of the fuel charge ignites spontaneously from heat and pressure

shortly aer ignition. This creates two ﬂame fronts

that meet and explode to create extreme hammering

pressures on a speciﬁc area of the piston. Detonation

generally occurs from using low octane fuels.

Preignition or ignition of the fuel charge before the timed spark can cause damage similar to detonation.

Preignition damage is oen more severe than

detonation damage. Preignition is caused by a hot spot in the combustion chamber from sources such

as glowing carbon deposits, blocked ﬁns, improperly

seated valve, or wrong spark plug. See Figure 9-12 for some common types of piston and ring damage.

Replacement pistons are available in STD and 0.08 mm (0.003 in.) oversize, which include new rings and piston pins. Service replacement piston ring sets are also available separately. Always use new piston rings when installing pistons. Never reuse old rings.

The cylinder bore must be deglazed before service ring sets are used.

Overheated or Deteriorated Oil

Figure 9-12. Common Types of Piston and Ring Damage.

9.10

Abrasive Scratched RingsStuck, Broken Rings

Scored Piston and Rings

Page 99

Some important points to remember when servicing piston rings:

1. If the cylinder bore is within the wear limits (refer to Section 1) and the old piston is within wear

limits, free of score or scuﬀ marks, the old piston

may be reused.

2. Remove old rings and clean up grooves. Never

reuse old rings.

3. Before installing the rings on the piston, place each of the top two rings in its running area in the cylinder bore and check the end gap (see Figure

9-13). Compare to the listed speciﬁcations.

Top and Middle Compression Ring End Gap New Bore

Top Ring .....................0.15/0.40 mm (0.006/0.016 in.)

Middle Ring ............... 0.30/0.55 mm (0.012/0.022 in.)

Max. Used Bore .........0.77 mm (0.030 in.)

Section 9

Inspection and Reconditioning

Figure 9-14. Measuring Piston Ring Side Clearance.

Install Piston Rings

To install piston rings, proceed as follows:

NOTE: Rings must be installed correctly. Ring

installation instructions are usually included with new ring sets. Follow instructions carefully. Use a piston ring expander to

install rings. Install the boom (oil control) ring ﬁrst and the top compression ring last.

Refer to Figure 9-15.

Figure 9-13. Measuring Piston Ring End Gap.

4. Aer installing the new compression (top and

middle) rings on the piston, check piston-to-ring side clearance. The maximum recommended side clearance for each ring is 0.04 mm (0.0016 in.). If

the side clearance is greater than speciﬁed, a new

piston must be used. Refer to Figure 9-14.

Top Compression Ring-to-Groove

Side Clearance ................................0.04 mm (0.0016 in.)

Middle Compression Ring-to-Groove

Side Clearance ...............................0.04 mm (0.0016 in.)

Piston Ring

End Gap

Identiﬁcation

Mark

Piston

Top Compression Ring

Center Compression Ring

Rails

Oil Control Ring (Three Piece)

Figure 9-15. Piston Ring Installation.

Expander

9.11

Page 100

Section 9 Inspection and Reconditioning

1. Oil Control Ring (Boom Groove): Install the

expander and then the rails. Make sure the ends of the expander are not overlapped.

2. Compression Ring (Center Groove): Install the center ring using a piston ring installation tool.

Make sure the identiﬁcation mark is up when the

ring is installed.

3. Compression Ring (Top Groove): Install the top ring using a piston ring installation tool. Make

sure the identiﬁcation mark is up when the ring

is installed.

Connecting Rods

Inspection and Service

Check the bearing area (big end) for score marks and excessive wear (measure running and side clearances; refer to Section 1. Service replacement connecting rods are available in STD crankpin size.

Oil Pump Assembly and Pressure Relief Valve

Inspection and Service

The closure plate must be removed to inspect and service the oil pump. Refer to the Disassembly and Reassembly Sections (8 and 10) for removal and reinstallation procedures. Check the oil pump and gears for cracks, damage, wear, and smooth rotation. Replace the pump if any binding is noted or reuse is questionable in any way.

A pressure relief valve is built into the oil pump to limit maximum pressure. It is not serviceable. If a problem exists with the pressure relief valve, the oil pump assembly should be replaced.

Oil Passages

Figure 9-16. Oil Passages in Closure Plate.

Oil Passages

Figure 9-17. Oil Passages in Passage Cover.

Use a new passage cover gasket and install the passage cover onto the closure plate. Reinstall the six mounting screws and torque to 4.0 N·m (35 in. lb.), following the sequence in Figure 9-18.

Closure Plate and Passage Cover

Inspection and Service

If disassembly was performed, inspect and ensure the oil passages in the closure plate and the passage cover are completely clean and not obstructed in any way. See Figures 9-16 and 9-17. Check straightness of the

passage cover if required, against a ﬂat surface.

9.12

Figure 9-18. Torque Sequence for Passage Cover.