Kohler CH980, CH960, CH1000, CH940 User Manual

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COMMAND PRO

CH940-CH980

HORIZONTAL CRANKSHAFT

SERVICE MANUAL

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

Section 2. T ools & 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 1

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.

NOTE

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

For Y our 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!

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(s).

2) Disconnect negative (-) battery cable from battery.

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 after 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 after it is turned off. Never operate the engine with heat shields or guards removed.

WARNING

1.1

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

WARNING 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.

Explosive Gas can cause fires and severe acid burns.

Charge battery only in a well ventilated area. Keep sources of ignition away.

Explosive Gas!

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

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.

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.

1.2

Engine Identification Numbers

When ordering parts, or in any communication involving an engine, always give the Model, Specification, and Serial Numbers, including letter suffixes if there are any.

The engine identification numbers appear on a decal, or decals, 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.

Command Engine Horizontal Crankshaft Numerical Designation

B. Spec. No.

C. Serial No.

Year Manufactured Code Code Year

37 2007 38 2008

C H 980 S

Version Code

S = Electric Start

CH940-0001 CH960-0001 CH980- 0001

Complete Spec. Number (Incorporating Model No. with V ariation No. of Basic Spec.)

3705810334

Factory Code

Figure 1-2. Explanation of Engine Identification Numbers.

1.3

Section 1 Safety and General Information

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. It is also recommended that a consistent brand of oil be used. 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 SG, SH, 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

°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 SG, SH, 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.

Kohler 10W-30

Refer to Section 6 - Lubrication System for detailed procedures on checking the oil, changing the oil and changing the oil filter.

Fuel Recommendations

WARNING: Explosive Fuel!

Gasoline is extremely flammable and its vapors can explode if ignited. Before servicing the fuel system, make sure there are no sparks, open flames or other sources of ignition nearby as these can ignite gasoline vapors. Disconnect and ground the spark plug leads to prevent the possibility of sparks from the ignition system.

General Recommendations

Purchase gasoline in small quantities that can be used within 30 days, and store only in clean, approved containers. Do not use gasoline left over from the previous season, unless treated with a fuel stabilizer (see Storage), to minimize gum deposits and ensure easy starting. Do not use gasoline containing Methanol, or 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 or higher. In countries using the Research method, it should be 90 octane minimum.

Unleaded gasoline is recommended as it leaves less combustion chamber deposits and reduces harmful exhaust emissions. 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.

Figure 1-3. Oil Container Logo.

1.4

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.

Periodic Maintenance Instructions

Section 1

Safety and General Information

WARNING: Accident al St arts!

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(s). 2) Disconnect negative (-) battery cable from battery.

Maintenance Schedule

These required maintenance procedures should be performed at the frequency stated in the table. They should also be included as part of any seasonal tune-up.

Frequency

Daily or Before

Starting Engine

Weekly

Seasonally or

Every 150 Hours

Every 200 Hours

Seasonally or

Every 300 Hours

Yearly or

Every 500 Hours

Every 600 Hours

¹Perform these maintenance procedures more frequently under extremely dusty, dirty conditions.

Have a Kohler Engine Service Dealer perform this service.

Maintenance Refer to:

• Fill fuel tank. Section 5

• Check oil level. Section 6

• Check air cleaner for dirty1, loose, or damaged parts. Section 4

• Check air intake and cooling areas, clean as necessary. Section 4

• Check filter minder or air cleaner element. Section 4

• Check air cleaner element. Section 4

• Replace fuel filter. Section 5

• Change oil. Oil filter is recommended. (More frequently under severe conditions.) Section 6

• Remove cooling shrouds and clean cooling areas1. Section 4

• Check oil cooler fins, clean as necessary. Section 6

• Check spark plug condition and gap. Section 7

• Change oil filter. Section 6

• Replace air cleaner element. Section 4

• Have solenoid shift starter disassembled and cleaned2. Section 7

• Have crankshaft splines lubricated2.

• Replace inner air cleaner element. Section 4

• Replace spark plugs. Section 7

Storage

If the engine will be out of service for 30 days or more, use the following storage procedure.

1. Clean the exterior surfaces of the engine. Avoid spraying water at the wiring harness or any of the electrical components.

2. Change the oil and oil filter while the engine is still warm from operation. See Changing 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 to 3 minutes to get stabilized fuel into the rest of the system. Close the fuel shut-off valve when the unit is being stored or transported.

To empty the system, run the engine until the tank and the system are empty.

4. Remove the spark plugs and add one tablespoon of engine oil into each spark plug hole. Install the spark plugs, but do not connect the plug leads. Crank the engine two or three revolutions.

5. Disconnect the battery or use a battery minder to keep the battery charged during storage.

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

1.5

Section 1 Safety and General Information

Dimensions in millimeters. Inch equivalents shown in [ ].

Figure 1-4. T ypical CH PRO Series Engine Dimensions with Heavy-Duty Air Cleaner.

1.6

Safety and General Information

General Specifications¹

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

CH940 ........................................................................................................25.4 kW (34 HP)

CH960 ........................................................................................................26.9 kW (36 HP)

CH980 ........................................................................................................28.3 kW (38 HP)

Bore ...................................................................................................................90 mm (3.54 in.)

Stroke ................................................................................................................ 78.5 mm (3.1 in.)

Displacement ...................................................................................................999 cc (61 cu. in.)

Compression Ratio ......................................................................................... 8.8:1

Dry Weight ......................................................................................................59.8 kg (132 lb.)

Oil Capacity (w/filter) - approximate,

determined by oil filter used ........................................................................ 2.7 L (2.9 U.S. qt.)

Angle of Operation - Maximum (At Full Oil Level) All Directions ......... 25°

Section 1

Blower Housing and Sheet Metal

M6 Shoulder Screw Torque

New, Untapped Hole (casting) .............................................................. 10.7 N·m (95 in. lb.)

Used, Tapped Hole (casting) ................................................................... 7.3 N·m (65 in. lb.)

New, Extruded Hole (sheet metal) ........................................................ 4.0 N·m (35 in. lb.)

Used, Extruded Hole (sheet metal) ........................................................ 2.0 N·m (17.7 in. lb.)

Mounting Clip (valley baffle)................................................................. 2.5 N·m (22.1 in. lb.)

M6 Screw Torque

New, Untapped Hole (casting) .............................................................. 10.7 N·m (95 in. lb)

Used, Tapped Hole (casting) ...................................................................7.3 N·m (65 in. lb)

Rectifier-Regulator Fastener Torque ........................................................... 2.0 N·m (18 in. lb.)

Oil Cooler Fastener Torque ............................................................................ 2.2 N·m (20 in. lb.)

Camshaft

End Play ...........................................................................................................0.3/1.3 mm (0.011/0.051 in.)

Running Clearance ......................................................................................... 0.025/0.063 mm (0.0010/0.0025 in.)

Bore I.D.

New ........................................................................................................... 20.000/20.025 mm (0.7874/0.7884 in.)

Max. Wear Limit ...................................................................................... 20.038 mm (0.7889 in.)

Camshaft Bearing Surface O.D.

New ........................................................................................................... 19.962/19.975 mm (0.7859/0.7864 in.)

Max. Wear Limit ...................................................................................... 19.959 mm (0.7858 in.)

Cam Lobe Profile (Minimum Dimension, Measured From Base Circle To Top Of Lobe)

Exhaust ............................................................................................................. 35 mm (1.3779 in.)

Intake ................................................................................................................35 mm (1.3779 in.)

¹Values are in Metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil

prior to assembly.

1.7

Section 1 Safety and General Information

Carburetor, Intake Manifold, and Air Cleaner

Intake Manifold Mounting Fastener Torque

Torque (Using Sequence) in Two Stages ...............................................first to 16.9 N·m (150 in. lb.)

finally to 22.6 N·m (200 in. lb.)

Carburetor/Air Cleaner Mounting Nut Torque .........................................7.9 N·m (70 in. lb.)

Air Cleaner Mounting Screw Torque (Into Intake Manifold) ...................9.9 N·m (88 in. lb.)

Control Bracket

Mounting Screw (Into Intake Manifold from Air Cleaner) Torque ......... 9.9 N·m (88 in. lb.)

Connecting Rod

Cap Fastener Torque (Torque In Increments) ............................................. 11.3 N·m (100 in. lb.)

Crankpin End I.D. @ 70°F

New ........................................................................................................... 44.030/44.037 mm (1.7334/1.7337 in.)

Max. Wear Limit ...................................................................................... 0.070 mm (0.0028 in.)

Connecting Rod-to-Crankpin Running Clearance

New ........................................................................................................... 0.030/0.055 mm (0.0012/0.0022 in.)

Max. Wear Limit ...................................................................................... 0.070 mm (0.0028 in.)

Connecting Rod-to-Crankpin Side Clearance ............................................ 0.30/0.59 mm (0.0118/0.0232 in.)

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

Piston Pin End I.D. @ 70°F

New ........................................................................................................... 19.023/19.015 mm (0.7489/0.7486 in.)

Max. Wear Limit ...................................................................................... 19.036 mm (0.7494 in.)

Crankcase

Governor Cross Shaft Bore I.D.

New ........................................................................................................... 8.025/8.050 mm (0.3159/0.3169 in.)

Max. Wear Limit ...................................................................................... 8.088 mm (0.3184 in.)

Breather Cover Fastener Torque .................................................................. 5.7 N·m (51 in. lb.)

Oil Drain Plug Torque .................................................................................... 21.4 N·m (15.7 ft. lb.)

Closure Plate

Closure Plate Fastener Torque ...................................................................... 24.4 N·m (216 in. lb.)

Reservoir (Oil)

Mounting Screw Torque ................................................................................ 24.4 N·m (216 in. lb.)

Crankshaft

End Play (Free) ................................................................................................ 0.30/1.50 mm (0.011/0.059 in.)

Crankshaft Bore (In Crankcase)

New, Without Main Bearing ................................................................. 50.00/50.025 mm (1.9685/1.969 in.)

With Main Bearing Installed .................................................................45.040/45.145 mm (1.7732/1.7773 in.)

Max. Wear Limit ...................................................................................... 45.158 mm (1.7778 in.)

Crankshaft to Sleeve Bearing (In Crankcase)

Running Clearance - New ...................................................................... 0.040/0.167 mm (0.0015/0.0065 in.)

1.8

Section 1

Safety and General Information

Crankshaft Bore (In Closure Plate) - New, Without Bearing ................... 50.025/50.00 mm (1.9694/1.9685 in.)

Crankshaft to Sleeve Bearing (In Closure Plate)

Running Clearance - New ...................................................................... 0.040/0.167 mm (0.0015/0.0065 in.)

Flywheel End Main Bearing Journal

O.D. - New ................................................................................................ 44.978/45.00 mm (1.770/1.771 in.)

O.D. - Max. Wear Limit ........................................................................... 44.90 mm (1.767 in.)

Max. Taper ................................................................................................0.022 mm (0.0009 in.)

Max. Out-of-Round ................................................................................. 0.025 mm (0.0010 in.)

Closure Plate End Main Bearing Journal

O.D. - New ................................................................................................ 44.978/45.00 mm (1.770/1.771 in.)

O.D. - Max. Wear Limit ........................................................................... 44.90 mm (1.767 in.)

Max. Taper ................................................................................................0.022 mm (0.0009 in.)

Max. Out-of-Round ................................................................................. 0.025 mm (0.0010 in.)

Connecting Rod Journal

O.D. - New ................................................................................................ 43.982/44.000 mm (1.731/1.732 in.)

O.D. - Max. Wear Limit ........................................................................... 43.97 mm (1.731 in.)

Max. Taper ................................................................................................0.018 mm (0.0007 in.)

Max. Out-of-Round ................................................................................. 0.025 mm (0.0010 in.)

Width ........................................................................................................53.00/53.09 mm (2.0866/2.0901 in.)

Crankshaft T .I.R.

PTO End, Crank in Engine ......................................................................0.279 mm (0.0110 in.)

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

Cylinder Bore

Cylinder Bore I.D.

New ........................................................................................................... 90.000/90.025 mm (3.543/3.544 in.)

Max. Wear Limit ...................................................................................... 90.075 mm (3.546 in.)

Max. Out-of-Round ................................................................................. 0.013 mm (0.00051 in.)

Max. Taper ................................................................................................ 0.013 mm (0.00051 in.)

Main Bearing I.D. (Crankcase/Closure Plate)

New (Installed) ........................................................................................ 45.040/45.145 mm (1.773/1.777 in.)

Max. Wear Limit ......................................................................................45.158 mm

Cylinder Head

Cylinder Head Fastener Torque

Head Bolt - Torque in Two Stages ......................................................... first to 22.6 N·m (200 in. lb.)

finally to 45.2 N·m (400 in. lb.)

Max. Out-of-Flatness ...................................................................................... 0.076 mm (0.003 in.)

Pipe Plug (3/4") Torque ................................................................................... 28.25 N·m (250 in. lb.)

Rocker Arm Screw Torque ............................................................................ 14.6 N·m (130 in. lb.)

Fan/Flywheel

Fan Fastener Torque .......................................................................................9.9 N·m (88 in. lb.)

Flywheel Retaining Screw Torque ............................................................... 67.8 N·m (50 ft. lb.)

1.9

Section 1 Safety and General Information

Grass Screen

Hex Stud Torque .............................................................................................. 9.9 N·m (88 in. lb.)

Mounting Screw Torque ................................................................................ 9.9 N·m (88 in. lb.)

Front Drive Shaft Screw Torque (Into Flywheel) ....................................... 24.4 N·m (216 in. lb.)

Governor

Governor Cross Shaft-to-Crankcase Running Clearance ........................ 0.025/0.087 mm (0.0009/0.0034 in.)

Governor Cross Shaft O.D.

New ........................................................................................................... 7.963/8.000 mm (0.3135/0.3149 in.)

Max. Wear Limit ...................................................................................... 7.936 mm (0.3124 in.)

Governor Gear Shaft-to-Governor Gear Running Clearance .................0.070/0.160 mm (0.0027/0.0063 in.)

Governor Gear Shaft O.D.

New ........................................................................................................... 5.990/6.000 mm (0.2358/0.2362 in.)

Max. Wear Limit ...................................................................................... 5.977 mm (0.2353 in.)

Governor Lever Nut Torque ......................................................................... 7.3 N·m (65 in. lb.)

Ignition

Spark Plug Type (Champion® or Equivalent) ............................................. XC10YC

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

Spark Plug Torque .......................................................................................... 24.4-29.8 N·m (18-22 ft. lb.)

Ignition Module Air Gap ...............................................................................0.28/0.33 mm (0.011/0.013 in.)

Ignition Module Fastener Torque ................................................................. 6.2 N·m (55 in. lb.) into new holes, or

4.0 N·m (35 in. lb.) into used holes

Lifter Feed Chamber

Cover/Baffle Screw Torque ............................................................................ 6.2 N·m (55 in. lb.)

Muffler

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

Oil Cooler

Mounting Screws Torque .............................................................................. 3.9 N·m (35 in. lb.)

Oil Filter

Oil Filter Torque .............................................................................................. 3/4-1 turn after gasket contact

Oil Filter Adapter/Housing

Mounting Screw Torque ................................................................................ 24.4 N·m (216 in. lb.)

Piston, Piston Rings, and Piston Pin

Piston-to-Piston Pin Running Clearance .................................................... 0.006/0.018 mm (0.0002/0.0007 in.)

Piston Pin Bore I.D.

New ........................................................................................................... 19.006/17.013 mm (0.7482/0.7485 in.)

Max. Wear Limit ...................................................................................... 19.025 mm (0.7490 in.)

Piston Pin O.D.

New ........................................................................................................... 18.995/19.000 mm (0.7478/0.7480 in.)

Max. Wear Limit ...................................................................................... 18.994 mm (0.7478 in.)

1.10

Section 1

Safety and General Information

Top Compression Ring-to-Groove Side Clearance .................................... 0.04/0.08 mm (0.0015/0.0031 in.)

Middle Compression Ring-to-Groove Side Clearance .............................. 0.04/0.08 mm (0.0015/0.0031 in.)

Oil Control Ring-to-Groove Side Clearance ...............................................0.03/0.19 mm (0.0011/0.0074 in.)

Top and Center Compression Ring End Gap

New Bore ..................................................................................................0.30/0.55 mm (0.011/0.021 in.)

Used Bore (Max.) ...................................................................................... 0.94 mm (0.037 in.)

Piston Thrust Face O.D.²

New ........................................................................................................... 89.953/89.967 mm (3.5414/3.5420 in.)

Max. Wear Limit ...................................................................................... 89.925 mm (3.540 in.)

Piston Thrust Face-to-Cylinder Bore² Running Clearance

New ........................................................................................................... 0.033/0.72 mm (0.0013/0.0028 in.)

Starter Assembly

Thru Bolt Torque

Delco-Remy (Solenoid Shift) .................................................................. 5.6-9.0 N·m (49-79 in. lb.)

Mounting Screw Torque ................................................................................ 15.3 N·m (135 in. lb.)

Brush Holder Mounting Screw Torque

Delco-Remy Starter ................................................................................. 2.5-3.3 N·m (22-29 in. lb.)

Solenoid (Starter)

Mounting Hardware Torque

Delco-Remy Starter ................................................................................. 4.0-6.0 N·m (35-53 in. lb.)

Nut, Positive (+) Brush Lead Torque

Delco-Remy Starter ................................................................................. 8.0-11.0 N·m (71-97 in. lb.)

Stator

Mounting Screw Torque ................................................................................ 6.2 N·m (55 in. lb.)

Throttle/Choke Control Bracket

Fastener Torque ............................................................................................... 9.9 N·m (88 in. lb.)

Valve Cover

Valve Cover Fastener Torque ........................................................................ 7.9 N·m (70 in. lb.)

Valves and Valve Lifters

Hydraulic Valve Lifter to Crankcase Running Clearance ........................ 0.012/0.050 mm (0.0004/0.0019 in.)

Intake Valve Stem-to-Valve Guide Running Clearance ........................... 0.038/0.076 mm (0.0015/0.0030 in.)

Exhaust Valve Stem-to-Valve Guide Running Clearance ........................0.050/0.088 mm (0.0020/0.0035 in.)

Intake Valve Guide I.D.

New ........................................................................................................... 7.038/7.058 mm (0.2771/0.2779 in.)

Max. Wear Limit ...................................................................................... 7.135 mm (0.2809 in.)

Exhaust Valve Guide I.D.

New ........................................................................................................... 7.038/7.058 mm (0.2771/0.2779 in.)

Max. Wear Limit ...................................................................................... 7.159 mm (0.2819 in.)

²Measure 11 mm (0.433 in.) above the bottom of the piston skirt at right angles to the piston pin.

1.11

Section 1 Safety and General Information

Valve Guide Reamer Size

Standard ...................................................................................................7.048 mm (0.2775 in.)

0.25 mm O.S. ............................................................................................. 7.298 mm (0.2873 in.)

Nominal Valve Face Angle ............................................................................45°

General Torque Values

Metric Fastener T orque Recommendations for S tandard Applications

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

Property Class

Noncritical

Fasteners

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

Into Aluminum

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

Property Class

Noncritical

Fasteners

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

Into Aluminum

1.12

Safety and General Information

English Fastener T orque Recommendations for St andard Applications

Section 1

Tightening Torque: N·m (in. lb.) + or - 20%

Bolts, Screws, Nuts and Fasteners Assembled Into Cast Iron or Steel

Grade 2 Grade 5 Grade 8

Size 8-32 2.3 (20) 2.8 (25) --------- 2.3 (20) 10-24 3.6 (32) 4.5 (40) --------- 3.6 (32) 10-32 3.6 (32) 4.5 (40) --------- --------- 1/4-20 7.9 (70) 13.0 (115) 18.7 (165) 7.9 (70) 1/4-28 9.6 (85) 15.8 (140) 22.6 (200) --------- 5/16-18 17.0 (150) 28.3 (250) 39.6 (350) 17.0 (150) 5/16-24 18.7 (165) 30.5 (270) --------- --------- 3/8-16 29.4 (260) --------- --------- --------- 3/8-24 33.9 (300) --------- --------- ---------

Grade 2 or 5 Fasteners Into Aluminum

Tightening Torque: N·m (ft. lb.) + or - 20%

Size 5/16-24 --------- ---------- 40.7 (30) --------3/8-16 --------- 47.5 (35) 67.8 (50) --------3/8-24 --------- 54.2 (40) 81.4 (60) --------7/16-14 47.5 (35) 74.6 (55) 108.5 (80) --------7/16-20 61.0 (45) 101.7 (75) 142.4 (105) --------1/2-13 67.8 (50) 108.5 (80) 155.9 (115) --------1/2-20 94.9 (70) 142.4 (105) 223.7 (165) --------9/16-12 101.7 (75) 169.5 (125) 237.3 (175) --------9/16-18 135.6 (100) 223.7 (165) 311.9 (230) --------5/8-11 149.2 (110) 244.1 (180) 352.6 (260) --------5/8-18 189.8 (140) 311.9 (230) 447.5 (330) --------3/4-10 199.3 (150) 332.2 (245) 474.6 (350) --------3/4-16 271.2 (200) 440.7 (325) 637.3 (470) ---------

Torque

Conversions

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

1.13

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

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2.3

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 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 lift the rocker arms or turn the crankshaft 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/Crankshaf t T ool.

2.4

Section 3

Troubleshooting

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 general common causes of engine troubles are listed below. Use these to locate the causing factors. Refer to the specific section(s) within this service manual for more detailed information.

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(s) disconnected.

6. Kill switch in off position.

7. Faulty spark plugs.

8. Faulty ignition module(s).

9. Carburetor solenoid malfunction.

10. Battery connected backwards.

11. Safety interlock system engaged.

11. Quality of fuel.

12. Flywheel key sheared.

13. Intake system leak.

Engine Will Not Crank

1. PTO drive is engaged.

2. Battery 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 or solenoid.

7. Seized internal engine components.

Engine Runs But Misses

1. Dirt or water in the fuel system.

2. Spark plug lead disconnected.

3. Poor quality of fuel.

4. Faulty spark plug(s).

5. Loose wires or connections that intermittently ground the ignition kill circuit.

6. Engine overheated.

7. Faulty ignition module or incorrect air gap.

8. Carburetor adjusted incorrectly.

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 throttle 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. Dirt or water in the fuel system.

3. Clogged fuel line.

4. Loose or faulty wires or connections.

5. Faulty or misadjusted choke or throttle controls.

6. Faulty spark plugs.

7. Low compression.

8. Weak spark.

9. Fuel pump malfunction causing lack of fuel.

10. Engine overheated-cooling/air circulation restricted.

Engine Will Not Idle

1. Dirt or water in the fuel system.

2. Stale fuel and/or gum in carburetor.

3. Faulty spark plugs.

4. Fuel supply inadequate.

5. Idle fuel adjusting needles 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.

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.

3.1

Section 3 Troubleshooting

Engine Knocks

1. Excessive engine load.

2. Low crankcase oil level.

3. Old or improper fuel.

4. Internal wear or damage.

5. Hydraulic lifter malfunction.

6. Quality of fuel.

7. 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 plugs.

8. Low compression.

9. Exhaust restriction.

10. Low battery.

11. Incorrect governor setting.

Engine Uses Excessive Amount of Oil

1. Incorrect oil viscosity/type.

2. Clogged, broken, or inoperative crankcase 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.

Oil Leaks from Oil Seals, Gaskets

1. Clogged, broken or inoperative crankcase breather.

2. Loose or improperly torqued fasteners.

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.

• Check for buildup of dirt and debris on the crankcase, cooling fins, grass screen, and other external surfaces. Dirt or debris on these areas are causes of higher operating temperatures and overheating.

• 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 that the engine has been under serviced.

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

• Check the oil level. Note if the oil level is within the operating range on the dipstick, or if it is low or overfilled.

• Check the condition of the oil. Drain the oil into a container - the oil 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 overrich carburetion, weak ignition, overextended oil change intervals or wrong weight or type of oil was used, to name a few.

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

After 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.

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.

• Check for obvious fuel and oil leaks, and damaged components. Excessive oil leakage can indicate a clogged or improperly-assembled breather, worn/damaged seals and gaskets, or loose or improperly-torqued fasteners.

3.2

Section 3

Troubleshooting

Basic Engine Tests

Crankcase Vacuum T est

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 assembled breather) can cause oil to be forced out at oil seals, gaskets, or other available spots.

Crankcase vacuum is best measured with either a water manometer or a vacuum gauge (see Section 2). Complete instructions are provided in the kits.

To test the crankcase vacuum with the manometer:

1. Insert the stopper/hose into the oil fill hole. Leave the other tube of manometer open to atmosphere. Make sure the shut off clamp is closed.

2. Start the engine and run at no-load high 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 less than specified (low/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 shut-off clamp before stopping the

engine.

To test the crankcase vacuum with the Vacuum/ Pressure Gauge Kit (see Section 2):

1. Remove the dipstick or oil fill plug/cap.

2. Install the adapter into the oil fill/dipstick tube opening.

3. Push the barbed fitting on the gauge solidly into the hole in the adapter.

4. Start the engine and bring it up to operating speed (3200-3600 RPM).

5. Check the reading on the gauge. If the reading is to the left of 0 on the gauge, vacuum or negative pressure is indicated. If the reading is to the right of 0 on the gauge, positive pressure is present.

Crankcase vacuum should be a minimum of 4 inches of water. If the reading is below the specification, or if pressure is present, check the table below for possible causes and remedies.

No Crankcase Vacuum/Pressure in Crankcase

Possible Cause

1. Crankcase breather clogged or inoperative.

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

3. Piston blow by or leaky valves (confirm by inspecting components).

4. Restricted exhaust.

Solution

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

Section 3 Troubleshooting

Compression T est

A compression test is best performed on a warm engine. Clean any dirt or debris away from the base of the spark plugs before removing them. Be sure the choke is off, and the throttle is wide open during the test. Compression should be at least 160 psi and should not vary more than 15% between cylinders.

Cylinder Leakdown T est

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 (see Section 2) is a relatively simple, inexpensive leakdown tester for small engines. The tester includes a quick disconnect for attaching the adapter hose, and a holding tool.

Leakdown T est Instructions

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

2. Remove the spark plug(s) and the air filter from engine.

3. Rotate the crankshaft until the piston (of cylinder being tested) is at top dead center (TDC) of the compression stroke. Hold the engine in this position while testing. The holding tool supplied with the tester can be used if the PTO end of the crankshaft is accessible. Lock the holding tool onto the crankshaft. Install a 3/8" breaker bar into the hole/slot of the holding tool, so it is perpendicular to both the holding tool and crankshaft PTO.

If the flywheel end is more accessible, use a breaker bar and socket on the flywheel nut/screw to hold it in position. An assistant may be needed to hold the breaker bar during testing. If the engine is mounted in a piece of equipment, it may be possible 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 attach it to the tester at this time.

5. Connect an air source of at least 50 psi to the tester.

6. Turn the regulator knob in the increase direction (clockwise) until the gauge needle is in the yellow set area at the low end of the scale.

7. Connect the tester quick-disconnect to the adapter hose while firmly holding the engine at TDC. Note the gauge reading and listen for escaping air at the carburetor intake, exhaust outlet, and crankcase breather.

8. Check the test results against the following table:

Leakdown Test Results

Air escaping from crankcase breather ......................................................Rings or cylinder worn.

Air escaping from exhaust system ............................................................Defective exhaust valve/improper seating.

Air escaping from carburetor .....................................................................Defective intake valve/improper seating.

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

Air Cleaner and Air Intake System

Section 4

Air Cleaner and Air Intake System

Section 4

Air Cleaners

General

These engines use a heavy-duty style air cleaner as shown in Figure 4-1, consisting of a cylindrical housing attached to the carburetor and intake manifold. The air cleaner housing contains a paper element and inner element, designed for longer service intervals. The system is CARB/EPA certified and the components should not be altered or modified in any way.

Heavy-Duty Style Air Cleaner

2. Check and clean the screen area on the inlet side. Pull the air cleaner paper element out of the housing on opposite side. See Figures 4-2 and 4-3.

Inlet Screen

Figure 4-2. Accessing Inlet Screen.

Paper Element

Figure 4-1. Heavy-Duty Style Air Cleaner.

Service

Weekly and every 150 hours: Check filter minder (if equipped), unhook the two retaining clips on each end and remove the end caps. Perform inspection of the paper element and inlet screen area.

Seasonally or every 300 hours of operation (more often under extremely dusty or dirty conditions), replace the paper element and check the inner element. Follow these steps.

1. Unhook the two retaining clips on each end and remove the end caps from the air cleaner housing.

Inner Element

Figure 4-3. Removing Elements.

3. After the paper element is removed, check the condition of the inner element. It should be replaced whenever it appears dirty, typically every other time the paper element is replaced or every 600 hours. Clean the area around the base of the inner element before removing it, so dirt does not get into the engine.

4.1

Section 4 Air Cleaner and Air Intake System

4. Do not wash the paper element and inner

element or use compressed air, this will damage the elements. Replace dirty, bent, or damaged elements with new genuine Kohler elements as required. Handle the new elements carefully; do not use if the sealing surfaces are bent or damaged.

5. Check all parts for wear, cracks, or damage, and that ejector area is clean. See Figure 4-4. Replace any damaged components.

Ejector Area

Air Intake/Cooling System

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

Seasonally or every 150 hours of operation (more often under extremely dusty or dirty conditions), remove the cylinder shrouds and blower housing. Clean the cooling fins and external surfaces as necessary. Make sure all shrouds are reinstalled.

Cylinder Shroud

Figure 4-4. Ejector Area.

6. Install the new inner element, followed by the paper element. Slide each fully into place in the air cleaner housing.

7. Reinstall the end caps and secure with the retaining clips. See Figure 4-1.

Air Cleaner Components

Whenever the air cleaner cover is removed, or the paper element or inner element are serviced, check the following:

Air Cleaner Housing - Make sure the housing is not damaged or broken and properly secured.

Air Cleaner Inlet - Make sure the air cleaner inlet is secured tightly to the carburetor and not cracked or damaged.

Breather Tube - Make sure the tube is attached to the air cleaner base and the breather cover.

Figure 4-5. Removing Shrouds for Cleaning.

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

Fuel System and Governor

Section 5

Fuel System and Governor

Section 5

Description

This section covers the standard carbureted fuel system used on these engines. The governor system used is covered at the end of this section.

WARNING: Explosive Fuel!

Fuel System Components

The typical carbureted fuel system and related components include the following:

• Fuel Tank and Valve

• Fuel Lines

• In-line Fuel Filter

• Fuel Pump

• Carburetor

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 allowing gravity to feed fuel to the carburetor.

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

Fuel Recommendations

General Recommendations

Purchase gasoline in small quantities that can be used within 30 days and store only in clean, approved containers. Do not use gasoline left over from the previous season, unless treated with a fuel stabilizer (see Storage in Section 1), to minimize gum deposits and ensure easy starting. Do not use gasoline containing Methanol, or 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 or higher. In countries using the Research fuel rating method, it should be 90 octane minimum.

Unleaded gasoline is recommended as it leaves less combustion chamber deposits and reduces harmful exhaust emissions. Leaded gasoline is not recommended .

Gasoline/Alcohol blends

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 Filter

Most engines are equipped with an in-line fuel filter. Periodically inspect the filter and replace with a genuine Kohler filter seasonally or every 150 operating hours.

Fuel Line

These engines use Low Permeation SAE 30 R7 rated fuel line; certified to meet emission requirements. Standard fuel line may not be used. Order replacement hose by part number through a Kohler Engine Service Dealer.

5.1

Section 5 Fuel System and Governor

Fuel System T ests

When the engine starts hard, or turns over but will not start, it is possible that the problem is in the fuel system. To find out if the fuel system is causing the problem, perform the following tests.

Troubleshooting – Fuel System Related Causes

T e st Conclusion

1. Check the following:

a. Make sure the fuel tank contains clean, fresh,

proper fuel.

b. Make sure the vent in fuel tank cap is open.

c. Make sure the fuel valve is open.

d. Make sure the fuel lines to fuel pump are

secured and in good condition.

2. Check for fuel in the combustion chamber.

a. Disconnect and ground spark plug leads.

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 fitting of

the fuel pump.

b. Hold the line below the bottom of the tank.

Open the shut-off valve (if so equipped) and observe flow.

4. Check the operation of the fuel pump.

a. Remove the fuel line from the inlet fitting 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, check for faulty

fuel pump (Test 4).

If fuel does not flow from the line, check the fuel tank cap vent, fuel pickup screen, in-line filter, shut-off valve, and fuel line. Correct any observed problem and reconnect the line.

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 a clogged fuel line. If the fuel line is unobstructed, check for overfilled crankcase and/or oil in pulse line. If none of the checks reveal the cause of the problem, replace the pump.

Fuel Pump

General

These engines use either a mechanical fuel pump, or optional remote-mounted electric fuel pump assembly. See Figures 5-1 and 5-2. Operation of the mechanical fuel pump occurs by direct lever/pump actuation off rocker arm movement. The pumping action causes the diaphragm on the inside of the pump to pull fuel in on its downward stroke and to push it into the carburetor on its upward stroke, internal check valves prevent fuel from going backward through the pump.

5.2

Fuel Pump

Figure 5-1. Mechanical Fuel Pump.

Section 5

Fuel System and Governor

Figure 5-2. Optional Electric Fuel Pump.

Fuel Pump - Replacement

Replacing the Mechanical Fuel Pump

The mechanical fuel pump is an integral part of the valve cover assembly and not serviced separately. See Figure 5-1.

1. Disconnect the fuel lines from the inlet and outlet fittings. Note orientation.

Self-Relieving Choke

Figure 5-3. Keihin Two-Barrel Carburetor.

Troubleshooting Checklist

When the engine starts hard, runs roughly, or stalls at low idle speed, check the following areas before adjusting or disassembling the carburetor.

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

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

Low Idle Fuel Adjustments (With Limiters)

Slow Jets Bowl Vent

Fuel Shut-Off Solenoid

2. Follow the procedure for replacing the valve cover (see Sections 8 and 10).

3. Reconnect the fuel lines to the inlet and outlet fittings and secure with the clamps.

Carburetor

General

Engines in this series are equipped with a Keihin BK two-barrel, side-draft carburetor with fixed main jets on a matching intake manifold. The carburetor features a self-relieving choke, serviceable slow jets, main jets, bowl drain and a fuel shutdown solenoid. See Figure 5-3.

WARNING: Explosive Fuel

• 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 for restrictions or faulty components as necessary.

• 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 (including precleaner if equipped) is clean and all air cleaner components are fastened securely.

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

If the engine is hard-starting, runs roughly, or stalls at low idle speed, it may be necessary to adjust or service the carburetor.

5.3

Section 5 Fuel System and Governor

Troubleshooting – Carburetor Related Causes

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 throttle opening).

Possible Cause/Probable Remedy

1. Low idle fuel mixture (some models)/speed improperly adjusted. Adjust the low idle speed tab, then adjust the low idle fuel needle.

2a. Clogged air cleaner. Clean or replace.

b. Choke partially closed during operation. Check the choke lever/

linkage to ensure choke is operating properly.

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

fuel needle (some models).

d. Float level is set too high. Adjust float according to Float

Replacement Procedure.

e. Dirt under the fuel inlet needle. Remove needle; clean needle and

seat and blow with compressed air.

f. Bowl vent or air bleeds plugged. Remove low idle fuel adjusting

needle. Clean vent, ports, and air bleeds. Blow out all passages with compressed air.

g. Leaky, cracked or damaged float. Submerge float to check for

leaks.

3. Engine runs lean (indicated by misfiring, loss of speed and power, governor hunting, or excessive throttle opening).

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

High Altitude Operation

When operating the engine at altitudes of 1500 m (5000 ft.) and above, the fuel mixture tends to get over-rich. This can cause conditions such as black, sooty exhaust smoke, misfiring, loss of speed and power, poor fuel economy, and poor or slow governor response.

To compensate for the effects of high altitude, special high altitude jet kits are available. The kits include new main jets, slow jets (where applicable), necessary gaskets, and O-Rings. Refer to the parts manual for the correct kit number.

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

fuel needle (some models).

b. Float level is set too low. Adjust float according to Float

Replacement Procedure.

c. Idle holes plugged; dirt in fuel delivery channels. Remove low

idle fuel adjusting needle. Clean main fuel jet and all passages; blow out with compressed air.

b. Dirt under fuel inlet needle. See Remedy 2e.

c. Bowl vents plugged. Blow out with compressed air.

d. Carburetor bowl gasket leaks. Replace gasket.

Fuel Shut-Off

Solenoid

Fuel Shut-off Solenoid

Most carburetors are equipped with a fuel shut-off solenoid. The solenoid is attached to the fuel bowl. See Figure 5-4. The solenoid has a spring-loaded pin that retracts when 12 volts is applied to the lead, allowing fuel flow to the main jets. When current is removed the pin extends blocking the fuel flow.

5.4

Figure 5-4. Fuel Shut-off Solenoid.

Below is a simple test, made with the engine off, that can determine if the solenoid is functioning properly:

1. Shut off fuel and remove the solenoid from the carburetor. When the solenoid is loosened and removed, gas will leak out of the carburetor.

Section 5

Fuel System and Governor

Have a container ready to catch the fuel.

2. Wipe the tip of the solenoid with a shop towel or blow it off with compressed air, to remove any remaining fuel. Take the solenoid to a location with good ventilation and no fuel vapors present. You will also need a 12 volt power source that can be switched on and off.

3. Be sure the power source is switched off. Connect the positive power source lead to the red lead of the solenoid. Connect the negative power source lead to the solenoid body.

4. Turn the power source on and observe the pin in the center of the solenoid. The pin should retract with the power on and return to its original position with the power off. Test several times to verify operation.

Carburetor Details

The Keihin BK two-barrel carburetor is a side-draft design. The circuits within the carburetor function as described following:

Float Circuit:

The fuel level in the bowl is maintained by the float and fuel inlet needle. The buoyant force of the float stops fuel flow when the engine is at rest. When fuel is being consumed, the float will drop and fuel pressure will push the inlet needle away from the seat, allowing more fuel to enter the bowl. When demand ceases, the buoyant force of the float will again overcome the fuel pressure, rising to the predetermined setting and stop the flow.

Slow & Mid-Range Circuit:

At low speeds the engine operates only on the slow circuit. As a metered amount of air is drawn through the slow air bleed jets, fuel is drawn through the two main jets and further metered through the slow jets. Air and fuel are mixed in the body of the slow jet and exit to the transfer port. From the transfer port the air fuel mixture is delivered to the idle progression chamber. From the idle progression chamber the air fuel mixture is metered through the idle port passages. At low idle when the vacuum signal is weak, the air/fuel mixture is controlled by the setting of the idle fuel adjusting screws. This mixture is then mixed with the main body of air and delivered to the engine. As the throttle plate opening increases, greater amounts of air/fuel mixture are drawn in through the fixed and metered idle progression holes. As the throttle plate opens further the vacuum signal becomes great enough so the main circuit begins to work.

Main (High-Speed) Circuit:

At high speeds/loads the engine operates on the main circuit. As a metered amount of air is drawn through the four air jets, fuel is drawn through the main jets. The air and fuel are mixed in the main nozzles and then enter the main body of airflow, where further mixing of the fuel and air occurs. This mixture is then delivered to the combustion chamber. The carburetor has a fixed main circuit; no adjustment is possible.

Carburetor Adjustments

Adjustment

NOTE: Carburetor adjustments should be made

only after the engine has warmed up.

The carburetor is designed to deliver the correct fuelto-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 adjusting needles are also set at the factory and normally do not need adjustment.

*NOTE: Engines operating at altitudes above

approximately 1500 m (5000 ft.) may require a special high altitude main jet. Refer to High Altitude Operation later in this section.

If, however, the engine is hard-starting or does not operate properly, it may be necessary to adjust or service the carburetor.

Low Idle Speed (RPM) Adjustment

1. Low Idle Speed (RPM) Setting: Place the throttle control in the idle or slow position. Set the low idle speed approximately 300 RPM* less than the intended or specified Governed Idle Speed, by turning the low idle speed adjusting screw in or out. Check the speed using a tachometer.

IMPORTANT: The Governed Idle Speed Adjustment must follow any resetting of the Low Idle Speed.

*NOTE: The actual low idle speed depends on

the application. Refer to the equipment manufacturer’s recommendations. The low idle speed for basic engines is 1200 RPM. To ensure best results when setting the low idle fuel needle, the low idle speed should be 1200 RPM (± 75 RPM).

5.5

Section 5 Fuel System and Governor

Low Idle Fuel Adjusters

(with Limiters)

Low Idle

Bowl Vent

Figure 5-5. Carburetor Adjustment Locations.

Low Idle Fuel Adjustment

NOTE: Engines will have fixed low idle or limiter

caps on the two idle fuel adjusting needles. Step 3 can only be performed within the limits allowed by the cap. Do not attempt to remove the limiter caps.

1. Start the engine and run at half throttle for 5 to 10 minutes to warm up. The engine must be warm before doing steps 2, 3, and 4.

2. Place the throttle control into the idle or slow

position. Adjust the low idle speed to 1200 RPM. Follow the Adjusting the Low Idle Speed (RPM) procedure.

3. Low Idle Fuel Needle(s) Setting: Place the throttle into the idle or slow position.

a. Turn one of the low idle fuel adjusting

needles out (counterclockwise) from the preliminary setting until the 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 settings. See Figure 5-6.

Speed (RPM) Adjustment Screw

Adjust to Midpoint

Rich

Left Side

Figure 5-6. Optimum Low Idle Fuel Settings.

Lean

Adjust to Midpoint

Rich

Right Side

Lean

Governed Idle System

A governed idle control system is used to maintain a desired idle speed regardless of ambient conditions (temperature, parasitic load, etc.) that may change. An outer secondary spring connected between the governor lever and the governed idle adjuster on the main bracket establishes the governed idle speed. See Figure 5-7.

Governed Idle Speed Adjustment

1. Make sure the governed idle spring is in the outer hole in the governor lever and the hole in the governed idle (outer) adjuster. See Figure 5-7.

2. Make sure the governor spring is in the inner slot of the governor lever and the hole in the high speed (inner) adjuster. See Figure 5-7. Pull the governor lever away from carburetor to the limit of its travel and check that the governor spring is loose and not under any tension. See Figure 5-8. Turn the high-speed (RPM) adjustment screw counter-clockwise (if required) until spring is loose.

Governor Spring

b. Repeat the procedure on the other low idle

adjustment needle.

4. Recheck/adjust the Low Idle Speed (RPM) to the specified setting.

5.6

Governed Idle Spring

Figure 5-7. Governor Springs Installed.

Hold/Pull Governor Lever Back

Governor Spring Must Be Loose In Slot

Section 5

Fuel System and Governor

Governed Idle Speed Adjustment Screw

Figure 5-8. Checking Spring Looseness.

3. Hold the governor lever away from the carburetor so the throttle lever is against the idle speed (RPM) adjustment screw of the carburetor. Start the engine and allow to warm up, then adjust the screw to set approximately 1200 RPM. Check using a tachometer. Turn the adjustment screw (inner) clockwise (in) to increase or counterclockwise (out) to decrease speed.

4. Release the governor lever and check that the throttle lever is in the idle (centered) position. See Figure 5-9. Turn the governed idle (outer) adjustment screw to obtain the equipment manufacturer’s recommended idle speed (1500-1800 RPM). The governed idle speed (RPM) is typically 300 RPM (approximate) higher than the low idle speed. See Figure 5-10.

Figure 5-10. Setting Governed Idle Speed RPM (Air Cleaner Removed For Clarity).

5. Move the throttle lever to the wide-open/full throttle position and hold in this position. Check the RPM using a tachometer. Turn the high speed screw to obtain the intended high speed no-load RPM. The governed idle speed must be set before making this adjustment. See Figure 5-11.

High Speed Adjustment

High Speed(RPM) Adjustment Screw

Screw

Full Throttle Position

Figure 5-9. Throttle Lever in Idle Position.

Figure 5-11. Setting High Speed RPM (Air Cleaner Removed for Clarity).

Carburetor Servicing

The following section covers the disassembly, various servicing procedures, and reassembly of the carburetor. For each procedure carefully inspect all components and replace those that are worn or damaged. The following should also be noted as service is performed.

• 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 shaft for wear or damage.

5.7

Section 5 Fuel System and Governor

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

• The choke plate is spring loaded. Check to make sure it moves freely on the shaft.

NOTE: The main and slow jets are fixed and side

specific and can be removed if required. Fixed jets for high altitudes are available.

Float Replacement

If symptoms described in the carburetor troubleshooting guide indicate float level problems, remove the carburetor from the engine to check and/ or replace the float. Use a float kit to replace the float, pin, float valve, clip, and screw.

1. Perform the removal procedures for the appropriate air cleaner and the carburetor outlined in Section 8 Disassembly.

2. Clean the exterior surfaces of dirt or foreign material before disassembling the carburetor. Remove the four mounting screws and carefully separate the fuel bowl from the carburetor. Do not damage the fuel bowl O-Rings. Transfer any remaining fuel into an approved container. Save all parts. Fuel can also be drained prior to bowl removal by loosening/removal of the bowl drain screw. See Figure 5-12.

Float

Inlet

Needle

Figure 5-13. Removing Float and Inlet Needle.

5. Attach the inlet needle to the plastic tang of the float with the wire clip. The formed 90° lip should point up, with the needle valve hanging down. See Figure 5-14.

Clip

Inlet Needle

Fuel Bowl

Bowl Drain Screw

Figure 5-12. Fuel Bowl Removed From Carburetor.

3. Remove the float pin screw and lift out the old float, pin and inlet needle. See Figure 5-13. Discard all of the parts. The seat for the inlet needle is not serviceable, and should not be removed.

4. Clean the carburetor bowl and inlet seat areas as required, before installing the new parts.

Float

Figure 5-14. Float and Inlet Needle Details.

6. Install the float and inlet needle down into the seat and carburetor body. Install the new pivot pin through the float hinge and secure with the new retaining screw. See Figure 5-15.

Retaining Screw

Pivot Pin

Figure 5-15. Installing Float Assembly.

5.8

Section 5

Fuel System and Governor

Figure 5-16. Checking Float Height.

7. Hold the carburetor body so the float assembly hangs vertically and rests lightly against the fuel inlet needle. The inlet needle should be fully seated but the center pin of the needle (on retainer clip end) should not be depressed. Check the float height adjustment.

NOTE: The inlet needle center pin is spring

loaded. Make sure the float rests against the fuel inlet needle without depressing the center pin.

8. The correct float height setting is 17 mm (0.669 in.) ± 1.5 mm (0.059 in.), measured from the float bottom to the body of the carburetor. See Figure 5-16. Replace the float if the height is different than specified. DO NOT attempt to adjust by bending float tab.

NOTE: Be sure to measure from the casting

surface, not the rubber gasket, if still attached.

Figure 5-17. Installing Fuel Bowl.

10. Install the carburetor and reassemble the engine as outlined in Section 10 Reassembly.

Disassembly/Overhaul

1. Clean the exterior surfaces of dirt or foreign material before disassembling the carburetor. Remove the four mounting screws and separate the fuel bowl from the carburetor. Transfer any remaining fuel into an approved container. Remove and discard the old O-Rings. Fuel can also be drained prior to bowl removal by loosening/removal of the bowl drain screw. See Figure 5-18.

Fuel Bowl

9. When the proper float height is obtained, carefully reinstall the fuel bowl onto the carburetor, using new O-Rings. Secure with the four original screws. Torque the screws to

2.5 ± 0.3 N·m (23 ± 2.6 in. lb.). See Figure 5-17.

Bowl Drain Screw

Figure 5-18. Fuel Bowl Removed From Carburetor.

NOTE: Further disassembly of the fuel bowl is

not necessary unless the Fuel Solenoid Kit, or Fuel Bowl Kit (obtained separately), will also be installed.

5.9

Section 5 Fuel System and Governor

2. Remove the float pin screw and lift out the old float, pin, and inlet needle. See Figure 5-19. Discard all the old parts. The seat for the inlet needle is not serviceable, and should not be removed.

Float

Inlet Needle

Figure 5-19. Removing Float and Inlet Needle.

3. Use an appropriate size flat screwdriver, and carefully remove the two main jets from the carburetor. Note and mark the jets by location for proper installation. The main jets may be size/side specific. After the main jets are removed, the main nozzles can be removed out through the bottom of the main towers. Note the orientation/direction of the nozzles. The end with the two raised shoulders should be out/down adjacent to the main jets. Save the parts for cleaning and reuse. See Figure 5-20.

See Figure 5-21 and 5-22. Save parts for cleaning and reuse unless a Jet Kit is also being installed. Clean the slow jets using compressed air. Do not use wire or carburetor cleaner.

Figure 5-21. Removing Screw and Washer.

Slow (Idle Fuel) Jets

O-Ring

Main Nozzles

Main Jets

Figure 5-20. Main Jets and Nozzles Removed.

4. Remove the screw securing the flat washer and ground lead (if equipped), from the top of the carburetor; then carefully pull (lift) out the two slow jets. The slow jets may be sized/side specific. Mark or tag the jets for proper reassembly. Note the small O-Ring on the bottom of each jet.

5.10

Figure 5-22. Slow Jets and O-Ring Detail.

5. Remove the idle speed (RPM) adjustment screw and spring from the carburetor. Discard the parts.

NOTE: The carburetor is now disassembled for

appropriate cleaning and installation of the parts in the overhaul kit. Further disassembly is not necessary. The throttle shaft assembly, fuel inlet seat, idle fuel adjustment screws with limiter, and carburetor body, are nonserviceable items and should not be removed. The choke shaft assembly is serviceable, however it should not be removed unless a Choke Repair Kit will be installed.

6. Clean the carburetor body, main jets, vent ports, seats, etc., using a good commercially available carburetor solvent. Keep away from plastic or rubber parts if non-compatible. Use clean, dry compressed air to blow out the internal channels and ports. Do not use metal tools or wire to clean orifices and jets. Inspect and thoroughly check the carburetor for cracks, wear, or damage. Inspect the fuel inlet seat for wear or damage. Check the spring loaded choke plate to make sure it moves freely on the shaft.

7. Clean the carburetor fuel bowl as required.

Section 5

Fuel System and Governor

Idle Speed Screw and Spring

8. Install the two main nozzles into the towers of the carburetor body. The end of the main nozzles with the two raised shoulders should be out/ down (adjacent to the main jets). Make sure the nozzles are completely bottomed. Carefully install the main jets into the towers of the carburetor body on the appropriate side, as identified when removal was performed. See Figure 5-23.

Nozzle End with T wo Shoulders (Out/Down)

Main Jets

Figure 5-23. Installing Main Nozzles and Main Jets.

9. Make sure the O-Ring near the bottom of each slow jet is new, or in good condition. Align and insert the two slow jets into the top of the carburetor. See Figure 5-22.

Figure 5-24. Installing Idle Speed Adjusting Screw and Spring.

12. Attach the inlet needle to the plastic tang of the float with the wire clip. The formed 90° lip should point up, with the needle valve hanging down. See Figure 5-25.

Float

Clip

Inlet Needle

Figure 5-25. Float and Inlet Needle Details.

13. Install the float and inlet needle down into the seat and carburetor body. Install the new pivot pin through the float hinge and secure with the new retaining screw. See Figure 5-26.

10. Install the large flat retaining washer and secure with the mounting screw, attaching the ground lead if originally secured by the screw.

11. Install the new idle speed (RPM) adjustment screw and spring onto the carburetor. Thread in until 3 or 4 threads are exposed, as an initial adjustment. See Figure 5-24.

Figure 5-26. Installing Float Assembly.

5.11

Section 5 Fuel System and Governor

14. Hold the carburetor body so the float assembly hangs vertically and rests lightly against the fuel inlet needle. The inlet needle should be fully seated but the center pin of the needle (on retainer clip end) should not be depressed. Check the float height adjustment.

NOTE: The inlet needle center pin is spring

loaded. Make sure the float rests against the fuel inlet needle without depressing the center pin.

15. The correct float height setting is 17 mm (0.669 in.) ± 1.5 mm (0.059 in.), measured from the float bottom to the body of the carburetor. See Figure 5-27. Replace the float if the height is different than specified. Do not attempt to adjust by bending the float tab.

NOTE: Be sure to measure from the casting

surface, not the rubber gasket, if still attached.

Figure 5-28. Installing Fuel Bowl.

Choke Repair

1. Remove the carburetor from the engine. Discard the old mounting gaskets for the air cleaner and carburetor.

2. Clean the areas around the choke shaft and the self-relieving choke mechanism thoroughly.

Figure 5-27. Checking Float Height.

16. When the proper float height is obtained, carefully reinstall the fuel bowl, using new O-Rings onto the carburetor. Secure with the four original screws. Torque the screws to

2.5 ± 0.3 N·m (23 ± 2.6 in. lb.). See Figure 5-28.

3. Remove and discard the plastic cap from the end of the choke lever/shaft assembly.

4. Note the position of the spring legs and the choke plate for correct reassembly later. See Figure 5-29. Remove the two screws attaching the choke plate to the choke shaft. Pull the shaft out of the carburetor body, note the preload of spring and discard the removed parts.

Figure 5-29. Choke Details.

5.12

5. Use a screw extractor (easy-out) and remove the original choke shaft bushing with the old choke lever from the carburetor housing. Save the bushing to use as a driver for installing the new bushing. Discard the old lever.

6. Clean the I.D. of both choke shaft bores as required.

Section 5

Fuel System and Governor

7. Insert the new bushing through the new choke lever from the outside, and start the bushing in the outer shaft bore. Position the choke lever so the protruding boss on the carburetor housing is between the two stops formed in the choke lever. See Figure 5-30.

Stops

Boss

Figure 5-30. Assembling Choke Lever .

8. Turn the old bushing upside down and use it as a driver to carefully press or tap the new bushing into the carburetor body until it bottoms. Check that the choke lever pivots freely without restriction or binding. See Figure 5-31.

Spring Ends

Choke Shaft

Figure 5-32. Choke Shaft and Spring Details.

10. Slide the choke shaft and spring into the carburetor. Pivot (preload) the shaft 3/4 turn counterclockwise with the inner leg of the spring against the formed stop within the choke lever as originally assembled. See Figures 5-29 and 5-33. The outer leg of the spring must still be behind the formed stop of the choke shaft.

Figure 5-31. Installing Bushing.

9. Install the new return spring onto the new choke shaft, so the outboard leg of the spring is behind the formed stop on the end of the choke shaft. See Figure 5-32.

NOTE: Make sure it stays in this location

during the following step.

Figure 5-33. Installing Choke Assembly Components.

11. Place a drop of Loctite new screw. Position and install the new choke plate to the flat side of the choke shaft. Start the two screws. Close the choke and check the plate alignment within the carburetor throat, then tighten the screws securely. Do not overtighten. See Figure 5-34.

on the threads of each

5.13

Section 5 Fuel System and Governor

Figure 5-34. Installing Choke Plate.

12. Check for proper operation and free movement of the parts. Install the new cap.

Always use new gaskets when servicing or reinstalling carburetors. Repair kits are available which include new gaskets and other components. Service/repair kits available for Keihin BK two-barrel carburetors and affiliated components are:

Carburetor Overhaul Kit Float Kit Fuel Solenoid Kit Bowl Kit High Altitude Kit (1525-3048 m/5,000-10,000 ft.) High Altitude Kit (Over 3048 m/10,000 ft.)

5.14

Section 5

Fuel System and Governor

1. Carburetor Body Subassembly

2. Idle Speed Screw

3. Idle Speed Spring

4. Screw

5. Ground Lead

6. Retaining Washer

7. Slow Jet - RH Side

8. Slow Jet - LH Side

9. O-Ring (Slow Jet) (2)

10. Fuel Bowl

11. O-Ring (Fuel Bowl - Upper)

Figure 5-35. Keihin BK Two-Barrel Carburetor - Exploded View.

Governor

General

The governor is designed to hold the engine speed constant under changing load conditions. Most engines are equipped with a centrifugal flyweight mechanical governor. The governor gear/flyweight mechanism of the mechanical governor is mounted inside the crankcase and is driven off the gear on the camshaft. This governor design works as follows:

12. O-Ring (Fuel Bowl - Lower)

13. Drain Screw

14. Bowl Screw (4)

15. Fuel Solenoid

16. Sealing Washer

17. Float

18. Pin

19. Screw

20. Float Clip

21. Float Valve/Inlet Needle

22. Main Nozzle - Right Side

• Centrifugal force acting on the rotating governor gear assembly causes the flyweights to move outward as speed increases. Governor spring tension moves them inward as speed decreases.

• As the flyweights move outward, they cause the regulating pin to move outward.

• The regulating pin contacts the tab on the cross shaft causing the shaft to rotate.

23. Main Nozzle - Left Side

24. Main Jet - Right Side

25. Main Jet - Left Side

26. Choke Dust Cap

27. Choke Shaft

28. Spring

29. Bushing

30. Choke Lever

31. Choke Plate

32. Choke Plate Screw (2)

5.15

Section 5 Fuel System and Governor

• One end of the cross shaft protrudes through the crankcase. The rotating action of the cross shaft is transmitted to the throttle lever of the carburetor through the external throttle linkage. See Figure 5-36.

Governor Lever

Governor Spring

Governed Idle Spring

Cross Shaft

Figure 5-36. Governor Linkage (Air Cleaner Removed for Clarity).

• When the engine is at rest, and the throttle is in the fast position, the tension of the governor spring holds the throttle plate open. When the engine is operating, the governor gear assembly is rotating. The force applied by the regulating pin against the cross shaft tends to close the throttle plate. The governor spring tension and the force applied by the regulating pin balance each other during operation, to maintain engine speed.

Initial Adjustment Procedure

Make this adjustment whenever the governor arm is loosened or removed from the cross shaft. See Figure 5-36 and adjust as follows:

1. Make sure the throttle linkage is connected to the governor arm and the throttle lever on the carburetor.

2. Loosen the hex nut holding the governor lever to the cross shaft.

3. Move the governor lever toward the carburetor as far as it will go (wide open throttle) and hold in this position.

4. Insert a long thin rod or tool into the hole on the cross shaft and rotate the shaft clockwise (viewed from the end) as far as it will turn, then torque the hex nut to 7.3 N·m (65 in. lb.).

High Speed (RPM) Adjustment

1. With the engine running, move the throttle control to fast. Use a tachometer to check the RPM speed.

2. Turn the inner adjustment screw outward to decrease, or inward to increase the RPM speed. Check RPM with a tachometer.

3. Stop when the desired RPM speed is obtained.

• When load is applied and the engine speed and governor gear speed decreases, the governor spring tension moves the governor arm to open the throttle plate wider. This allows more fuel into the engine, increasing the engine speed. As the speed reaches the governed setting, the governor spring tension and the force applied by the regulating pin will again offset each other to hold a steady engine speed.

Adjustments

NOTE: Do not tamper with the governor setting.

Overspeed is hazardous and could cause personal injury.

General

The governed speed setting is determined by the position of the throttle control. It can be variable or constant, depending on the engine application.

High Speed (RPM) Adjustment Screw

Figure 5-37. High Speed RPM Adjustment (Air Cleaner Removed For Clarity.

5.16

Section 6

Lubrication System

Section 6

Lubrication System

General

This engine uses a full pressure lubrication system. This system delivers oil under pressure to the crankshaft, camshaft, and connecting rod bearing surfaces. In addition to lubricating the bearing surfaces, the lubrication system supplies oil to the hydraulic valve lifters.

A high-efficiency gerotor pump is located in the closure plate. The oil pump maintains high oil flow and oil pressure, even at low speeds and high operating temperatures. A pressure relief valve limits the maximum pressure of the system.

Service

The closure plate must be removed to service the oil pickup, the pressure relief valve, and the oil pump. Refer to the appropriate procedures in Sections 8, 9, and 10.

Oil Recommendations

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 6-1.

Use high-quality detergent oil of API (American Petroleum Institute) service class SG, SH, 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

°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)

Kohler 10W-30

Figure 6-1. Oil Container Logo.

The top portion of the symbol shows service class such as API SERVICE CLASS SJ. The symbol may show additional categories such as SH, SG/CC, or CD. The center portion shows the viscosity grade such as SAE 10W-30. If the bottom portion shows Energy Conserving, it means that oil is intended to improve fuel economy in passenger car engines.

6.1

Section 6 Lubrication System

Checking 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:

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

2. Clean the area around the dipstick before removing it. This will help to keep dirt, grass clippings, etc., out of the engine.

3. Remove the dipstick; wipe oil off. Reinsert the dipstick into the tube until fully seated. See Figure 6-2.

Oil Fill Cap

Dipstick

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 above the ‘‘F” mark on the dipstick.

Changing Oil and Oil Filter

Changing Oil

Change oil seasonally or every 150 hours of operation, (more frequently under severe conditions). Refill with service class SG, SH, SJ, or higher oil as specified in the Viscosity Grades table on page 6.1.

Change the oil 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 as follows:

1. Clean the areas around one of the drain plugs, oil fill cap, and dipstick.

2. Remove one of the oil drain plugs, oil fill cap, and dipstick. Be sure to allow ample time for complete drainage.

Figure 6-2. Dipstick and Oil Fill Cap Locations

4. Remove dipstick and check oil level. The level should be between the ‘‘F’’ and ‘‘L’’ marks. If low, remove the oil fill cap and add oil of the proper type up to the “F” mark. Reinstall oil fill cap and dipstick.

Operating Range

Figure 6-3. Oil Level Marks on Dipstick.

Oil Drain Plug

Figure 6-4. Oil Drain Plug (Starter Side).

Oil Drain Plug

6.2

Figure 6-5. Oil Drain Plug (No. 2 Side).

3. Reinstall the drain plug and torque to 21.4 N·m (15.7 ft. lb.).

4. Fill the crankcase, with new oil of the proper type, to the “F” mark on the dipstick. Refer to Oil Type on page 6.1. Always check the level with the dipstick before adding more oil.

Oil Fill Cap

Figure 6-6. Removing Oil Fill Cap.

5. Reinstall the oil fill cap and tighten securely. Reinstall dipstick.

Section 6

Lubrication System

Figure 6-8. Optional Remote Mounted Oil Filter.

Replace the oil filter as follows:

1. Before removing the oil filter, clean the area around the oil filter and housing to keep dirt and debris out of the engine. Remove the old filter. On crankcase mounted oil filter housings, a spring loaded inner cup allows automatic oil drainback into the crankcase as the oil filter is removed. Wipe off the surface where the oil filter mounts.

2. Drain the oil from the engine crankcase.

Changing Oil Filter

Replace the oil filter seasonally (150 hours), or at least every other oil change (every 300 hours of operation). Always use a genuine Kohler oil filter. The oil filter on most engines is located on top of the crankcase between the cylinders. Some models use a remote mounted oil filter. See Figures 6-7 and 6-8.

Oil Filter

Figure 6-7. Engine Mounted Oil Filter.

3. Allow ample time for the oil to drain from the crankcase.

4. Reinstall the drain plug and torque to 21.4 N·m (15.7 ft. lb.).

5. Apply a thin film of clean oil to the rubber gasket on the new filter. Partial prefilling of the oil filter is recommended.

6. Install the replacement oil filter to the filter adapter or oil cooler. Turn the oil filter clockwise until the rubber gasket contacts the oil filter housing (not inner cup), then tighten the filter an additional 3/4-1 turn.

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

8. Start the engine and check for oil leaks. Correct any leaks before placing the engine into service. Check oil level to be sure it is up to but not over the “F” mark.

6.3

Section 6 Lubrication System

Service Oil Cooler

These engines are equipped with an oil cooler mounted under the No. 2 side cylinder shroud, separate from the oil filter. See Figure 6-9.

Oil

Cylinder Shroud

Figure 6-9. Oil Cooler.

Inspect and clean the oil cooler every 150 hours of operation (more frequently under severe conditions).

In order to be effective, the oil cooler must be kept free of debris.

To service the oil cooler, clean the outside of fins with a brush, vacuum, or compressed air. If required, remove the two screws holding the cooler unit to the backing shroud asseembly. Carefully pull the cooler outward and clean the underside. After cleaning, reinstall the oil cooler to the backing shroud with the two mounting screws.

Cooler

Oil Cooler

Figure 6-11. Cleaning Underside of Oil Cooler.

Oil Sentry™

General

Some engines are equipped with an optional Oil Sentry™ oil pressure monitor switch. See Figure 6-12. If the oil pressure drops below an acceptable level, the Oil Sentry™ will either shut off the engine or activate a warning signal, depending on the application.

The pressure switch is designed to break contact as the oil pressure increases above 7-11 psi, and make contact as the oil pressure decreases below 7-11 psi.

On stationary or unattended applications (pumps, generators, etc.), the pressure switch can be used to ground the ignition module to stop the engine. On vehicular applications (lawn tractors, mowers, etc.) the pressure switch can only be used to activate a low oil warning light or signal.

Figure 6-10. Cleaning Top of Oil Cooler.

6.4

NOTE: Make sure the oil level is checked before each

use and is maintained up to the “F” mark on

the dipstick. This includes engines equipped with Oil Sentry™ .

Pressure Switch

Figure 6-12. Oil Sentry™ Pressure Switch.

Section 6

Lubrication System

Installation

The Oil Sentry™ pressure switch is installed in the closure plate pressure port. See Figure 6-12. On engines not equipped with Oil Sentry™ the installation hole is sealed with a 1/8-27 N.P.T.F. pipe plug.

To install the switch, follow these steps:

1. Apply pipe sealant with Teflon® (Loctite® No.

59241 or equivalent) to the threads of the switch.

2. Install the switch into the tapped hole in the closure plate. See Figure 6-12.

3. Torque the switch to 10.1 N·m (90 in. lb.).

T esting

Compressed air, a pressure regulator, pressure gauge, and a continuity tester are required to test the 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. As the pressure increases through the range of

7-11 psi the tester should indicate a change to no continuity (switch open). The switch should remain open as the pressure is increased to 90 psi maximum.

3. Gradually decrease the pressure through the range of 7-11 psi. The tester should indicate a change to continuity (switch closed) down to 0 psi.

4. Replace the switch if it does not operate as specified.

6.5

Section 7

Electrical System and Components

Section 7

Electrical System and Components

This section covers the operation, service, and repair of the electrical system components. Systems and components covered in this section are:

• Spark Plugs

• Battery and Charging System

• Electric Starter

Spark Plugs

Engine misfire or starting problems are often caused by a spark plug that has improper gap or is in poor condition.

The engine is equipped with the following spark plugs:

Type: The standard spark plug is a Champion

XC10YC (Kohler Part No. 62 132 04-S). Equivalent alternate brand plugs can also be used.

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

Every 200 hours of operation, remove each spark plug. Check its condition and either reset the gap or replace with a new plug as necessary. Replace spark plugs every 600 hours. To service the plugs, perform the following steps:

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

Wire Gauge

Spark Plug

Ground

Electrode

Figure 7-1. Servicing Spark Plug.

4. Reinstall the spark plug into the cylinder head and torque to 24.4-29.8 N·m (18-22 ft. lb.).

Inspection

Inspect each spark plug 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.

0.76 mm (0.030 in.) Gap

1. Before removing each spark plug, clean the area around the base of the plug to keep dirt and debris out of the engine.

2. Remove the plug and check its condition. See Inspection following this procedure. Replace the plug if necessary.

NOTE: Do not clean 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.

Normal and fouled plugs are shown in the following photos:

7.1

Section 7 Electrical System and Components

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 set to the proper gap and reused.

Carbon Fouled: Soft, sooty, black deposits indicate incomplete combustion caused by a restricted air cleaner, over rich carburetion, weak ignition, or poor compression.

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

Overheated: Chalky, white deposits indicate very high combustion temperatures. This condition is usually accompanied by excessive gap erosion. Lean carburetor settings, an intake air leak, or incorrect spark timing are normal causes for high combustion temperatures.

Worn: On a worn plug, the center electrode will be rounded and the gap will be greater than the specified gap. Replace a worn spark plug immediately.

7.2

Section 7

Electrical System and Components

Battery

General

A 12-volt battery with 400 cold cranking amps (cca) is generally recommended for starting in all conditions. A smaller capacity battery is often sufficient if an application is started only in warmer temperatures. Refer to the following table for minimum capacities based on anticipated ambient temperatures. The actual cold cranking requirement depends on engine size, application, and starting temperatures. The cranking requirements increase as temperatures decrease and battery capacity shrinks. Refer also to the operating instructions of the equipment this engine powers for specific battery requirements.

Battery Size Recommendations

2. Keep the cables, terminals, and external surfaces of the battery clean. A build-up of corrosive acid or grime on the external surfaces can cause the battery to self-discharge. Self-discharge occurs rapidly when moisture is present.

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

NOTE: Do not allow the baking soda solution to

enter the cells as this will destroy the electrolyte.

Battery Test

To test the battery, you will need a DC voltmeter. Perform the following steps (See Figure 7-2):

1. Connect the voltmeter across the battery terminals.

2. Crank the engine. If the battery drops below 9 volts while cranking, the battery is too small, discharged, or faulty.

If the battery charge is insufficient to turn over the engine, recharge the battery.

Battery Maintenance

Regular maintenance is necessary to prolong battery life.

WARNING: Explosive Gas!

Batteries produce explosive hydrogen gas while being charged. To prevent a fire or explosion, charge batteries only in well ventilated areas. Keep sources of ignition away from the battery at all times. Keep batteries out of the reach of children. Remove all jewelry when servicing batteries.

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

NOTE: Do not overfill the battery. Poor

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

DC V oltmeter

Battery

Figure 7-2. Battery V oltage T est.

7.3

Section 7 Electrical System and Components

Electronic CD Ignition System

Kill Switch or ‘‘Off’’ Position of Key Switch

(0.28/0.33 mm)

0.011/0.013 in. Air Gap

Figure 7-3. Capacitive Discharge (Fixed Timing) Ignition System. Operation of CD Ignition System

Capacitive Discharge with Fixed Timing

This system (Figure 7-3) consists of the following components:

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

• Two electronic capacitive-discharge ignition modules (Figure 7-3) which mount on the engine crankcase .

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

• Two spark plugs.

The timing of the spark is controlled by the location of the flywheel magnet group as referenced to engine top dead center.

Ignition Modules

Spark Plug

Magnet

Flywheel

SCS

Figure 7-4. Capacitive Discharge Ignition Module Schematic.

Operation: As the flywheel rotates, the magnet grouping passes the input coil (L1). The corresponding magnetic field induces energy into the input coil (L1). The resultant pulse is rectified by D1 and charges capacitor C1. As the magnet assembly completes its pass, it activates the triggering device (L2), which causes the semiconductor switch (SCS) to turn on. With the device switch ON, the charging capacitor (C1) is directly connected across the primary (P) of the output transformer (T1). As the capacitor discharges, the current initiates a fast rising flux field in the transformer core. A high voltage pulse is generated from this action into the secondary winding of the transformer. This pulse is delivered to the spark plug gap. Ionization of the gap occurs, resulting in an arc at the plug electrodes. This spark ignites the fuel-air mixture in the combustion chamber.

Troubleshooting CD Ignition Systems

The CD ignition systems are designed to be trouble free for the life of the engine. Other than periodically checking/replacing the spark plugs, no maintenance or timing adjustments are necessary or possible. Mechanical systems do occasionally fail or break down however, so the following troubleshooting information is provided to help you get to the root of a reported problem.

The CD ignition systems produce a high-energy electric spark, but the spark must be discharged, or damage to the system can result. Do not crank or run an engine with a spark plug lead disconnected. Always provide a path for the spark to discharge to ground.

Spark Plug

CAUTION: High-Energy Electric Spark!

7.4

Section 7

Electrical System and Components

Reported ignition problems are most often due to poor connections. Before beginning the test procedure, check all external wiring. Be certain all ignitionrelated wires are connected, including the spark plug leads. Be certain all terminal connections fit snugly. Make sure the ignition switch is in the run position.

NOTE: The CD ignition systems are sensitive to

excessive load on the kill lead. If a customer complains of hard starting, low power, or misfire under load, it may be due to excessive draw on the kill circuit. Perform the appropriate test procedure.

Test Procedure for Standard (Fixed Timing) CD Ignition System

Isolate and verify the trouble is within the engine ignition system.

1. Locate the plug connectors where the wiring harnesses from the engine and equipment are joined. Separate the connectors and remove 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.

a. If the problem is gone, the electrical

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

2. Test for spark on both cylinders with Kohler ignition tester (see Section 2). Disconnect one spark plug lead and connect it to the post terminal of the tester. Connect the clip to a good ground, not to the spark plug. Crank the engine and observe the tester spark gap. Repeat the procedure on the other cylinder. Remember to reconnect the first spark plug lead.

a. If one side is not firing, check all wiring,

connections, and terminations on that side. If wiring is okay, replace ignition module and retest for spark.

b. If the tester shows spark, but the engine

misses or won’t run on that cylinder, try a new spark plug.

c. If neither side is firing, recheck position of

ignition switch and check for shorted kill lead.

Battery Charging System

General

Most engines are equipped with a 15, 20, or 25 amp regulated charging system. See Figures 7-5, 7-6, 7-7, and 7-8.

NOTE: Observe the following guidelines to avoid

damage to the electrical system and components:

b. If the problem persists, the condition is

associated with the ignition or electrical system of the engine. Leave the kill lead isolated until all testing is completed.

**NOTE: If the engine starts or runs during any of the

testing, you may need to ground the kill lead to shut it down. Because you have interrupted the kill circuit, it may not stop using the switch.

• Make sure the battery polarity is correct. A negative (-) ground system is used.

• Disconnect the rectifier-regulator plug and/or the wiring harness plug before doing any electric welding on the equipment powered by the engine. Also, disconnect all other electrical accessories in common ground with the engine.

• Prevent the stator (AC) leads from touching or shorting while the engine is running. This could damage the stator.

7.5

Section 7 Electrical System and Components

15/20/25 Amp Regulated Charging System

Figure 7-5. 25 Amp Stator and 20/25 AmpRectifierRegulator.

NOTE: 20 amp charging systems use a 15 amp stator with a 25 amp rectifier-regulator.

Figure 7-6. 15 Amp St ator and Rectifier-Regulator.

Figure 7-7. Wiring Diagram-15/20/25 Amp Regulated Battery Charging System with Fixed Timing, Four Pin Connector.

7.6

Section 7

Electrical System and Components

Figure 7-8. Wiring Diagram15/20/25 Amp Regulated Battery Charging System with Fixed Timing, Five Pin Connector, Key Switch, and Fuse.

7.7

Section 7 Electrical System and Components

Stator

The stator is mounted on the crankcase behind the flywheel. Follow the procedures in Section 9 Disassembly and Section 11 - Reassembly if stator replacement is necessary.

Rectifier-Regulator

The rectifier-regulator is mounted on the backing shroud assembly. See Figure 7-9. To replace it, disconnect the plug, remove the two mounting screws, and ground lead.

NOTE: When installing the rectifier-regulator, take

note of the terminal positions and install the plug correctly.

Ground Lead

Figure 7-10. Connected Adapter.

2. Connect the tester ground lead (with spring clamp) to the body of the rectifier-regulator.

3. Connect the red lead and one of the black leads to the pair of terminals on the open end of the tandem adapter lead (connections are not location specific).

RectifierRegulator

Connector Plug

Figure 7-9. Rectifier-Regulator.

Testing of the rectifier-regulator may be performed as follows, using the appropriate Rectifier-Regulator Tester (see Section 2).

To Test –

NOTE: Disconnect all electrical connections attached

to the rectifier-regulator. Testing may be performed with the rectifier-regulator mounted or loose. The figures show the part removed from the engine for clarity. Repeat the applicable test procedure two or three times to determine the condition of the part.

20/25 Amp Rectifier-Regulators

1. Connect the single lead adapter in between the B+ (center) terminal of rectifier-regulator being tested and the squared single end of the tandem adapter lead. See Figure 7-10.

4. Connect the remaining black lead from the tester to one of the outer AC terminals on the rectifierregulator. See Figure 7-11.

Figure 7-11. Connected Tester.

7.8

Section 7

Electrical System and Components

5. Plug the tester into the proper AC outlet/power for tester being used. Turn on the power switch. The POWER light should be illuminated and one of the four status lights may be on as well. See Figure 7-12. This does not represent the condition of the part.

Figure 7-12. Powered Tester.

6. Press the TEST button until a click is heard and then release. See Figure 7-13. Momentarily one of the four lights will illuminate indicating the partial condition of the part.

*NOTE: A flashing LOW light can also occur as a

result of an inadequate ground lead connection. Make certain the connection location is clean and the clamp is secure.

15 Amp Rectifier-Regulators

1. Connect the tester ground lead (with spring clamp) to the body of the rectifier-regulator being tested.

2. Connect the tester red lead to the B+ terminal of the rectifier-regulator and the two black tester leads to the two AC terminals. See Figure 7-14.

Figure 7-13. Pressing T est Button.

a. If the OK (green) light comes on, disconnect

the tester black lead attached to one AC terminal and reconnect it to the other AC terminal. Repeat the test. If the OK (green) light comes on again, the part is good and may be used.

b. If any other light is displayed* in either of the

tests, the rectifier-regulator is faulty and should not be used.

Figure 7-14. T ester Connected to 15 Amp RectifierRegulator.

3. Plug the tester into the proper AC outlet/power for tester being used. Turn on the power switch. See Figure 7-12. The POWER light should be illuminated and one of the four status lights may be on as well. This does not represent the condition of the part.

4. Press the TEST button until a click is heard and then release. See Figure 7-13. Momentarily one of the four status lights will illuminate, indicating the condition of the part.

a. If the OK (green) light comes on and stays

steady, the part is good and may be used.

b. If any other light is displayed,* the rectifier-

regulator is faulty and should not be used.

*NOTE: A flashing LOW light can also occur as a

result of an inadequate ground lead connection. Make certain connection location is clean and clamp is secure.

7.9

Section 7 Electrical System and Components

Troubleshooting Guide

15/20/25 Amp Battery Charging Systems

When problems occur in keeping the battery charged or the battery charges at too high a rate, the problem can usually be found somewhere in the charging system or with the battery.

NOTE: Always zero ohmmeter on each scale before testing to ensure accurate readings. Voltage tests should

be made with the engine running at 3600 RPM - no load. The battery must be good and fully charged.

Problem Test Conclusion

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 battery. Connect DC voltmeter from loose end of B+ lead to negative terminal of battery. With engine running at 3600 RPM, read voltage on voltmeter.

1. If voltage is 13.8-14.7 and charge rate increases when load is applied, the charging system is OK and battery 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).

No Charge

to Battery

Battery

Continuously

Charges at

High Rate

If voltage is 13.8 volts or more, place a minimum load of 5 amps* on battery to reduce voltage. Observe ammeter.

*NOTE: Turn on lights, if 60 watts or more.

Or place a 2.5 ohm, 100 watt resistor across battery terminals.

2. Remove connector from rectifier-regulator. With engine running at 3600 RPM, measure AC voltage across stator leads using an AC voltmeter.

3a. With engine stopped, measure the

resistance across stator leads using an ohmmeter.

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.

2. If voltage is 28 volts or more, stator is OK.

Rectifier-regulator is faulty. Replace the rectifier-regulator.

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 0.064/0.2 ohms, the stator is

OK.

If the resistance is infinity ohms, stator is open. Replace stator.

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 leads are shorted to ground. Replace stator.

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

system is OK. The battery is unable to hold a charge. Service battery or replace as necessary.

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

7.10

(-)

Section 7

Electrical System and Components

Rectifier-Regulator

DC V oltmeter

(+)

Flywheel Stator

Ammeter

Battery

Figure 7-15. Connections for T esting Charging System.

Electric Starting Motors

The engines in this series use solenoid shift starters. A Delco-Remy solenoid shift starter is typically used.

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 attempts. Failure to follow these guidelines can burn out the starter motor.

NOTE: If the engine develops sufficient speed to

disengage the starter but does not keep running (a false start), the engine rotation must be allowed to come to a complete stop before attempting 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.

Starter Removal and Installation

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

Operation – Solenoid Shift Starter

When power is applied to the starter the electric solenoid moves the drive pinion out onto the drive shaft and into mesh with the flywheel ring gear. When the pinion reaches the end of the drive shaft it rotates the flywheel and cranks the engine.

When the engine starts and the start switch is released the starter solenoid is deactivated, the drive lever moves back, and the drive pinion moves out of mesh with the ring gear into the retracted position.

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

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

NOTE: Do not drop the starter or strike the starter

frame. Doing so can damage the starter.

7.11

Section 7 Electrical System and Components

Troubleshooting Guide – S tarting Difficulties

Problem Possible Fault Correction

Starter Does Not Energize

Starter

Energizes

but T urns

Slowly

Battery

Wiring

Starter Switch

or Solenoid

Battery

Brushes

Transmission

Engine

1. Check the specific gravity of the battery. If low, recharge or replace battery as necessary.

1. Clean corroded connections and tighten loose connections.

2. Replace wires in poor condition and with frayed or broken insulation.

1. By-pass the switch or solenoid with a jumper wire. If starter cranks normally, replace the faulty components. Remove and perform individual solenoid test procedure. See pages 7.20 and

7.21.

1. Check the specific gravity of the battery. If low, recharge or replace battery as necessary.

1. Check for excessively dirty or worn brushes and commutator. Clean 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.

Delco-Remy Starters

Figure 7-16. Completed Delco-Remy Starter.

Starter Disassembly

1. Remove the hex nut and disconnect the positive (+) brush lead/bracket from the solenoid terminal.

2. Remove the three Torx head screws securing the solenoid to the starter. See Figure 7-17.

Torx Head Screws

Figure 7-17. Removing Solenoid Screws.

3. Unhook the plunger pin from the drive lever. Remove the gasket from the recess in the housing. See Figures 7-18 and 7-19.

NOTE: Test procedure for checking starter solenoid

is on pages 7.20 and 7.21.

7.12

Section 7

Electrical System and Components

Figure 7-18. Solenoid Removed from Starter.

Figure 7-19. Removing Plunger.

4. Remove the two thru (larger) bolts. See Figure 7-20.

Figure 7-21. Removing Commutator End Plate Assembly .

6. Remove the frame from the armature and drive end cap. See Figure 7-22.

Figure 7-22. Starter Frame Removed.

7. Remove the drive lever pivot bushing and backing plate from the end cap. See Figure 7-23.

Figure 7-20. Removing Thru Bolts.

5. Remove the commutator end plate assembly, containing the brush holder, brushes, springs, and locking caps. Remove the thrust washer from inside the commutator end. See Figure 7-21.

Figure 7-23. Removing Backing Plate and Pivot Bushing.

7.13

Section 7 Electrical System and Components

8. Take out the drive lever and pull the armature out of the drive end cap. See Figure 7-24.

9. Remove the thrust washer from the armature shaft. See Figure 7-24.

Figure 7-24. Armature and Lever Removed.

10. Push the stop collar down to expose the retaining ring. See Figure 7-25.

11. Remove the retainer from the armature shaft. Save the stop collar.

NOTE: Do not reuse the old retainer.

Figure 7-26. Removing Retaining Ring.

12. Remove the drive pinion assembly from the armature.

13. Clean the parts as required.

Figure 7-25. Retaining Ring Detail.

NOTE: Do not soak the armature or use solvent

when cleaning. Wipe clean using a soft cloth, or use compressed air.

Screw Drive End Cap

Collar

Retaining Ring

Stop

Drive

Armature

Washer

Tube

Plunger

Spring Lever

Plate

Plug

Solenoid

Frame & Field

Brush Holder

Nut

Commutator End Plate

Screw

7.14

Bolt

Figure 7-27. Delco-Remy Starter.

Section 7

Electrical System and Components

Inspection

Drive Pinion

Check and inspect the following areas:

a. The pinion teeth for abnormal wear or damage.

b. The surface between the pinion and the clutch

mechanism for nicks, or irregularities which could cause seal damage.

c. Check the drive clutch by holding the clutch

housing and rotating the pinion. The pinion should rotate in one direction only.

Brushes and Springs

Inspect both the springs and brushes for wear, fatigue, or damage. Measure the length of each brush. The minimum length for each brush is 7.6 mm (0.300 in.). See Figure 7-28. Replace the brushes if they are worn undersize, or their condition is questionable.

Commutator O.D.

Mica Insulation

Figure 7-29. Commutator Mica Inspection.

2. Use an ohmmeter set to the Rx1 scale. Touch the probes between two different segments of the commutator, and check for continuity. See Figure 7-30. Test all the segments. Continuity must exist between all or the armature is bad.

Insulation Check

Wear Limit Length

7.6 mm (0.300 in.)

Figure 7-28. Checking Brushes.

Armature

1. Clean and inspect the commutator (outer surface). The mica insulation must be lower than the commutator bars (undercut) to ensure proper operation of the commutator. See Figure 7-29.

Continuity Check Armature Coil

Figure 7-30. Checking Armature.

3. Check for continuity between the armature coil segments and the commutator segments. See Figure 7-30. There should be no continuity. If continuity exists between any two, the armature is bad.

4. Check the armature windings/insulation for shorting.

Shift Fork

Check that the shift fork is complete, and the pivot and contact areas are not excessively worn, cracked, or broken.

7.15

Section 7 Electrical System and Components

Brush Replacement

The brushes and springs are serviced as a set (4). Use a new Kohler Brush and Spring Kit, if replacement is necessary.

1. Perform steps 1-5 in Starter Disassembly.

2. Remove the two screws securing the brush holder assembly to the end cap (plate). Note the orientation for reassembly later. See Figure 7-31. Discard the old brush holder assembly.

Figure 7-31. Removing Brush Holder.

3. Clean the component parts as required.

Starter Service

Clean the drive lever and armature shaft. Apply Kohler electric starter drive lubricant (see Section 2) (Versilube G322L or Mobil Temp SHC 32) to the lever and shaft. Clean and check the other starter parts for wear or damage as required.

Starter Reassembly

1. Apply drive lubricant (see Section 2) to the armature shaft splines. Install the drive pinion onto the armature shaft.

2. Install and assemble the stop collar/retainer assembly.

a. Install the stop collar down onto the

armature shaft with the counter bore (recess) up.

b. Install a new retainer in the larger (rear)

groove of the armature shaft. Squeeze with a pliers to compress it in the groove.

c. Slide the stop collar up and lock it into

place, so the recess surrounds the retainer in the groove. If necessary, rotate the pinion outward on the armature splines against the retainer to help seat the collar around the retainer.

4. The new brushes and springs come preassembled in a brush holder with a protective sleeve that will also serve as an installation tool. See Figure 7-32.

Figure 7-32. Service Brush Kit.

5. Perform Steps 10-13 in the Starter Reassembly sequence. Installation must be done after the armature, drive lever, and frame are installed, if the starter has been disassembled.

Figure 7-33. Installing Stop Collar and Retainer.

NOTE: Always use a new retainer. Do not reuse

old retainers which have been removed.

7.16

Section 7

Electrical System and Components

3. Install the offset thrust (stop) washer so the smaller offset of the washer faces the retainer/ collar. See Figure 7-34.

Thrust Washer

Figure 7-34. Installing Thrust Washer.

4. Apply a small amount of oil to the bearing in the drive end cap, and install the armature with the drive pinion.

5. Lubricate the fork end and center pivot of the drive lever with drive lubricant (see Section 2). Position the fork end into the space between the captured washer and the rear of the pinion.

6. Slide the armature into the drive end cap, and at the same time seat the drive lever into the housing.

7. Install the backup washer, followed by the rubber grommet, into the matching recess of the drive end cap. The molded recesses in the grommet should be out, matching and aligned with those in the end cap. See Figure 7-36.

Figure 7-36. Installing Backup Washer and Grommet.

8. Install the frame, with the small notch forward, onto the armature and drive end cap. Align the notch with the corresponding section in the rubber grommet. Install the drain tube in the rear cutout, if it was removed previously. See Figure 7-37.

NOTE: Correctly installed, the center pivot

section of the drive lever will be flush or below the machined surface of the housing which receives the backup washer. See Figure 7-35.

Figure 7-35. Installing Armature and Pivot Lever.

Figure 7-37. Installing Frame and Drain Tube.

7.17

Section 7 Electrical System and Components

9. Install the flat thrust washer onto the commutator end of the armature shaft. See Figure 7-38.

Thrust Washer

Figure 7-38. Installing Thrust W asher .

10. Starter reassembly when replacing the Brushes/

Brush Holder Assembly:

a. Hold the starter assembly vertically on the

end housing, and carefully position the assembled brush holder assembly, with the supplied protective tube, against the end of the commutator/armature. The mounting screw holes in the metal clips must be up/ out. Slide the brush holder assembly down into place around the commutator, and install the positive (+) brush lead grommet in the cutout of the frame. See Figure 7-39. The protective tube may be saved and used for future servicing.

Starter reassembly when not replacing the Brushes/ Brush Holder Assembly:

a. Carefully unhook the retaining caps from

over each of the brush assemblies. Do not lose the springs. See Figure 7-40.

Figure 7-40. Removing Retaining Clips.

b. Position each of the brushes back in their

slots so they are flush with the I.D. of the brush holder assembly. Insert the Brush Installation Tool (with extension), or use the tube described above from a prior brush installation, through the brush holder assembly, so the holes in the metal mounting clips are up/out.

c. Install the brush springs and snap on the four

retainer caps. See Figure 7-41.

Figure 7-39. Installing Brush Holder Assembly with Supplied Tube.

7.18

Figure 7-41. Brush Installation T ool with Extension.

d. Hold the starter assembly vertically on the

end housing, and carefully place the tool (with extension) and assembled original brush holder assembly onto the end of the armature shaft. Slide the brush holder assembly down into place around the commutator, install the positive (+) brush lead grommet in the cutout of the frame. See Figure 7-42.

Section 7

Electrical System and Components

Figure 7-44. T orquing Brush Holder Screws.

13. Hook the plunger behind the upper end of the drive lever, and install the spring into the solenoid. Insert the three mounting screws through the holes in the drive end cap. Use these to hold the solenoid gasket in position, then mount the solenoid. Torque the screws to

4.0-6.0 N·m (35-53 in. lb.).

Figure 7-42. Installing Brush Holder Assembly using T ool with Extension.

11. Install the end cap onto the armature and frame, aligning the thin raised rib in the end cap with the corresponding slot in the grommet of the positive (+) brush lead.

12. Install the two thru bolts, and the two brush holder mounting screws. Torque the thru bolts to

5.6-9.0 N·m (49-79 in. lb.). Torque the brush holder mounting screws to 2.5-3.3 N·m (22-29 in. lb.). See Figures 7-43 and 7-44.

14. Connect the positive (+) brush lead/bracket to the solenoid and secure with the hex nut. Torque the nut to 8-11 N·m (71-97 in. lb.). Do not overtighten. See Figure 7-45.

Positive Brush Lead

Figure 7-45. Positive (+) Brush Lead Connection.

Figure 7-43. T orquing Thru Bolts.

7.19

Section 7 Electrical System and Components

Solenoid Test Procedure

Solenoid Shift Style Starters

Disconnect all leads from the solenoid including the positive brush lead attached to the lower stud terminal. Remove the mounting hardware and separate the solenoid from the starter for testing.

Test 1. Solenoid Pull-In Coil/Plunger Actuation T est.

Use a 12 volt power supply and two test leads. Connect one lead to the flat spade S/start terminal on the solenoid. Momentarily* connect the other lead to the lower large post terminal. See Figure 7-46. When the connection is made the solenoid should energize (audible click), and the plunger retract. Repeat the test several times. If the solenoid fails to activate, it should be replaced.

*NOTE: DO NOT leave the 12 volt test leads

connected to the solenoid for any time over what is necessary for performing each of the individual tests. Internal damage to the solenoid may otherwise occur.

12 volt T est Leads Momentary Connection Only

VOM Leads

Figure 7-47. T esting Pull-In Coil/Solenoid Contact Continuity .

T est 3. Solenoid Hold-In Coil Function Test.

Connect one 12 volt test lead to the flat spade S/start terminal on the solenoid, and the other lead to the body or mounting surface of the solenoid. Then, manually push the plunger In and check if the Hold-In coil holds the plunger retracted. See Figure 7-48. Do not allow the test leads to remain connected to the solenoid for a prolonged period of time. If the plunger fails to stay retracted, the solenoid should be replaced.

12 volt T est Leads Momentary Connection Only

Figure 7-46. T esting Pull-In Coil/Plunger Actuation.

T est 2. Solenoid Pull-In Coil/Cont act Continuity T est.

Use an ohmmeter set to the audible or Rx2K scale, and connect the two ohmmeter leads to the two large post terminals. Perform the preceding test (1) and check for continuity. See Figure 7-47. The ohmmeter should indicate continuity, if no continuity is indicated the solenoid should be replaced. Repeat test several times to confirm condition.

Manually Push Plunger In

12 volt T est Leads Connect Only Long Enough toT est

Figure 7-48. T esting Hold-In Coil/Function T est.

7.20

T est 4. Solenoid Hold-In Coil/Contact Continuity T est.

Use an ohmmeter set to the audible or Rx2K scale, and connect the two ohmmeter leads to the two large post terminals. Perform the preceding test (3) and check for continuity. See Figure 7-49. The meter should indicate continuity. If no continuity is indicated, the solenoid should be replaced. Repeat test several times to confirm condition.

Section 7

Electrical System and Components

VOM Meter Leads

Plunger Pushed In

12 volt T est Leads

Figure 7-49. T esting Hold-In Coil/Solenoid Cont act Continuity.

7.21

Section 8

Disassembly

Section 8

Disassembly

WARNING: Accident al St arts!

General

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.

Typical Disassembly Sequence

The following sequence is suggested for complete engine disassembly. The sequence can be varied to accommodate options or special equipment.

1. Disconnect spark plug leads.

2. Shut off fuel supply.

3. Drain oil from crankcase and remove oil filter.

4. Remove muffler.

5. Remove cylinder shrouds and blower housing.

6. Remove electric starter motor.

7. Remove air cleaner assembly.

8. Remove control bracket, governor springs, and lever.

9. Remove carburetor.

10. Remove Oil Sentry™ (if equipped).

11. Remove baffles and intake manifold.

12. Remove oil cooler.

13. Remove oil filter housing and oil filter adapter.

14. Remove ignition modules.

15. Remove grass screen and cooling fan

16. Remove flywheel.

17. Remove stator, rectifier-regulator, and wiring harness.

18. Remove backing shroud assembly.

19. Remove spark plugs.

20. Remove valve covers and fuel pump.

21. Remove cylinder heads and hydraulic lifters.

22. Disassemble cylinder heads.

23. Remove breather assembly.

24. Remove oil reservoir and pickup screen.

25. Remove closure plate assembly.

26. Remove camshaft.

27. Remove connecting rods with pistons and rings.

28. Remove crankshaft.

29. Removal of governor gear assembly.

30. Remove governor yoke, cross shaft, and seal.

31. Remove lifter feed cover and gaskets.

32. Remove flywheel and PTO end oil seals.

33. Removal of main bearings.

Disconnect Spark Plug Leads

1. Disconnect the leads from the spark plugs. See Figure 8-1.

NOTE: Pull on boot only, to prevent damage to

spark plug lead.

Figure 8-1. Disconnect Both Spark Plug Leads.

8.1

Section 8 Disassembly

Shut Off Fuel Supply Drain Oil from Crankcase and Remove Oil

Filter

1. Clean the oil filter and housing area. Remove and discard the oil filter. See Figure 8-2.

Figure 8-2. Removing Oil Filter.

2. Remove the dipstick and one of the oil drain plugs.

3. Allow ample time for the oil to drain from the crankcase.

Remove Muffler

1. Remove the exhaust system and attaching hardware from the engine.

Remove Cylinder Shrouds and Blower Housing

1. Remove the top mounting screw and loosen the two shoulder screws on each side. Lift off the two cylinder shrouds. See Figure 8-5.

Cylinder Shroud

Figure 8-3. Removing Dipstick from Tube.

Figure 8-5. Removing Cylinder Shrouds.

2. Remove the four mounting screws and separate the blower housing from the lower half. See Figure 8-6.

Figure 8-6. Removing Blower Housing.

Drain Plug (Starter Side Shown)

Figure 8-4. Oil Drain Plug Location.

8.2

Section 8

Disassembly

Remove Electric Starter Motor

1. Disconnect the leads from the starter.

2. Remove the two hex flange screws and starter. See Figure 8-7.

Mounting Screws

Figure 8-7. Removing Electric Starter.

Remove Air Cleaner Assembly

1. Disconnect the breather hose from the air cleaner, and the formed vent hose from the vent port on the carburetor.

3. Remove the two screws securing the air cleaner and main control bracket to the intake manifold bosses. See Figure 8-9.

Mounting Screws

Figure 8-9. Mounting Screws.

4. Remove the air cleaner as an assembly from the engine. See Figure 8-10.

2. Remove the four hex flange nuts, ground lead, and choke return spring bracket from the mounting studs. See Figure 8-8.

Vent Hose

Mounting

Nuts

Breather Hose

Bracket

Figure 8-8. Air Cleaner Mounting Details.

Figure 8-10. Removing Air Cleaner Assembly.

8.3

Section 8 Disassembly

Removing Control Bracket, Governor Springs, and Lever

1. Unhook the governed idle and governor springs from the controls on the main bracket and governor lever. Note the color, location and position of each. See Figure 8-11.

2. Disconnect the throttle linkage and dampening spring from the governor lever at the small bushing. See Figure 8-11.

3. Carefully pry off the pal nut, remove the two washers (note assembly order), and disconnect the choke linkage from the pivot lever. Do not lose any parts. Secure remaining pivot parts with tape to avoid losing them. Always use a new pal nut during reassembly. See Figure 8-11.

Pal Nut

Governor Springs

Governor Lever

Figure 8-13. Removing Governor Lever.

Remove Carburetor

WARNING: Explosive Fuel!

Throttle

Choke Linkage

Figure 8-11. Disconnect Control Linkages and Governor Springs.

4. Remove the rear mounting screw on each side and lift off the control bracket. See Figure 8-12.

Control Bracket

Mounting Screw

Linkage

1. Disconnect the fuel shut-off solenoid lead.

2. Remove the fuel inlet hose from the carburetor or fuel pump. Properly contain any remaining fuel.

3. Remove the carburetor and linkages with choke return components as an assembly. See Figure 8-14.

Figure 8-14. Removing Carburetor.

Figure 8-12. Removing Control Bracket.

5. Loosen the hex flange nut and remove the governor lever from cross shaft. See Figure 8-13.

8.4

4. Remove the carburetor gasket.

5. The carburetor and linkages can be separated as necessary.

Section 8

Disassembly

Remove Oil Sentry™ (If Equipped)

1. Disconnect the lead from the Oil Sentry™ switch.

2. Remove the Oil Sentry™ switch from the closure plate. See Figure 8-15.

Pressure Switch

Figure 8-15. Oil Sentry™ Switch Location in Closure Plate.

Remove Baffles and Intake Manifold

1. Remove the screws securing the valley baffles to the cylinder heads and backing shroud assembly.

2. Remove the four screws securing each of the outer cylinder baffles in place. Two of the screws are accessed from the backing shroud side. See Figure 8-17.

Mounting Screws

Figure 8-17. Removing Outer Cylinder Baffles.

3. Remove the four hex flange screws securing the intake manifold to the cylinder heads. Cut any wire ties that secure the wiring harness or leads to the intake manifold.

4. Remove the intake manifold and gaskets. See Figure 8-18.

Figure 8-16. Removing Valley Baffles.

Mounting Locations

Figure 8-18. Removing Intake Manifold.

Mounting Locations

8.5

Section 8 Disassembly

Remove Oil Cooler

1. Remove the two oil cooler mounting screws. Do not lose any washers (if used). See Figure 8-19.

Figure 8-19. Removing Oil Cooler Mounting Screws.

2. Loosen the clamps and disconnect each of the hoses from the oil cooler. See Figure 8-20.

Housing Mounting Screw

Figure 8-21. Removing Oil Filter Housing From Adapter .

Perform the following only if the oil filter housing assembly requires individual servicing.

a. Remove the nipple from the cup and oil filter

housing. See Figure 8-22.

NOTE: New clamps are recommended any time

disassembly is performed, or if clamps have been loosened (expanded) several times.

Figure 8-20. Disconnecting Hoses From Oil Cooler.

Remove Oil Filter Housing and Oil Filter Adapter

1. Remove the screw securing the oil filter housing and individual O-Rings to the adapter. Carefully separate the parts. See Figure 8-21.

Nipple

Figure 8-22. Removing Nipple.

b. Remove the oil filter cup and spring from

housing. See Figure 8-23.

Housing

Spring

Cup

Nipple

NOTE: Further disassembly of the oil filter

housing assembly is not required unless individual servicing must be performed. Follow substeps a, b, and c.

8.6

Figure 8-23. Disassembled Cup and Spring.

c. Remove the rubber valve and spring from the

cup. See Figure 8-24.

Section 8

Disassembly

Cup

Valve

Figure 8-24. Rubber Valve and Spring Removed from Cup.

2. Remove the screw securing the oil filter adapter and individual O-Rings to the crankcase, then carefully separate the parts. See Figure 8-25.

Spring

Adapter Mounting

Mounting

Screw

Ignition Modules

Figure 8-26. Removing Ignition Modules.

Remove Grass Screen and Cooling Fan

1. Remove the screws, attaching hardware and hex studs securing the grass screen, stiffeners and cooling fan to the flywheel. See Figures 8-27, 8-28 and 8-29.

Adapter

Figure 8-25. Removing Oil Filter Housing Adapter.

Remove Ignition Modules

1. Rotate the flywheel so the magnet is away from the modules.

2. Remove the mounting screws and disconnect the kill lead from the ignition modules. Note the position of ignition modules. See Figure 8-26.

Figure 8-27. Removing Grass Screen Fasteners.

Figure 8-28. Removing Mounting Studs.

8.7

Section 8 Disassembly

Mounting

Screws

Figure 8-29. Removing Fan.

Remove Flywheel

1. Use a flywheel strap wrench or holding tool (see Section 2) to hold the flywheel and loosen the hex flange screw securing the flywheel to the crankshaft. See Figure 8-30.

NOTE: Always use a flywheel strap wrench or

holding tool to hold the flywheel when loosening or tightening the flywheel screw. Do not use any type of bar or wedge to hold the flywheel. Use of such tools could cause the flywheel to become cracked or damaged.

Figure 8-31. Removing Flywheel with a Puller.

4. Remove the woodruff key from the crankshaft.

Remove Stator, Rectifier-Regulator, and Wiring Harness

1. Disconnect the plug from the rectifier-regulator. If the B+ (center) lead must be removed from the plug, use a small flat tool to bend the locking tang. Then remove the lead.

2. Remove the mounting screws securing the rectifier-regulator to the backing shroud assembly. Note the location of the ground lead. If the rectifier-regulator is not being replaced, it may remain mounted to the lower blower housing. See Figure 8-32.

Ground Lead

Figure 8-30. Removing Flywheel Fastener Using Holding T ool.

2. Remove the hex flange screw and washer.

3. Use a puller to remove the flywheel from the crankshaft. See Figure 8-31.

NOTE: Always use a flywheel puller to remove

the flywheel from the crankshaft. Do not strike the crankshaft or flywheel, as these parts could become cracked or damaged.

8.8

RectifierRegulator

Plug

Figure 8-32. Rectifier-Regulator Details.

3. Remove the two screws securing the stator to the crankcase and carefully separate the stator wires from the blower housing clips.

Molded Clips

Mounting Screws

Figure 8-33. Removing Stator.

4. Unhook the wiring harness from the molded clips if it is being serviced separately. See Figure 8-34.

Wiring Harness

Molded Clip

Section 8

Disassembly

Remove Spark Plugs

1. Remove the spark plug from each cylinder head.

Figure 8-36. Removing Spark Plugs.

Remove Valve Covers and Fuel Pump

WARNING: Explosive Fuel!

Figure 8-34. Removing Wiring Harness.

Remove Backing Shroud Assembly

1. Remove the four mounting screws securing the backing shroud assembly to the crankcase. See Figure 8-35.

Backing Shroud Assembly

Screws

Figure 8-35. Removing Backing Shroud Mounting Screws.

NOTE: Based on the style of fuel pump used refer to

the following when removing valve covers.

Mechanical Fuel Pump

1. The mechanical fuel pump is part of the valve cover and not serviced separately. Remove with the valve cover. Disconnect the fuel lines at the fuel pump fittings. See Figure 8-37. Properly contain any remaining fuel.

Figure 8-37. Disconnecting Fuel Lines.

8.9

Section 8 Disassembly

Electric Fuel Pump

1. Removal will be determined based on mounted location and application. Disconnect the lead connections, fuel line connections, and mounting hardware as required. Properly contain any remaining fuel.

Valve Covers

1. Remove the screw and grommet securing each valve cover.

2. Remove the valve cover and gasket from each cylinder head. Note the locations of individual valve covers if they are different. See Figure 8-38.

Spacer

Washers

Figure 8-40. Removing Cylinder Head Fasteners.

3. Mark the position of the push rods as either intake or exhaust and cylinder 1 or 2. Push rods should always be reinstalled in the same positions.

Figure 8-38. Removing Valve Covers.

Remove Cylinder Heads and Hydraulic Lifters

1. Remove the pipe plug from the cylinder head to access the screw in the upper center location. See Figure 8-39.

Pipe Plug

4. Carefully remove the push rods, cylinder head and head gasket. See Figure 8-41.

5. Repeat the procedure for the other cylinder head.

Figure 8-41. Removing Cylinder Head Assembly.

6. Remove the lifters from the lifter bores. Use a Hydraulic Lifter Tool. Do not use a magnet to remove lifters. Mark the lifters by location, as either intake or exhaust and cylinder 1 or 2. Hydraulic lifters should always be reinstalled in the same position. See Figures 8-42 and 8-43.

Figure 8-39. Removing Pipe Plug.

2. Remove the five hex flange screws securing each cylinder head. Note the locations of washers and spacer. See Figure 8-40.

8.10

NOTE: The exhaust lifters are located on the

output shaft side of the engine while the intake lifters are located on the fan side of the engine. The cylinder head number is embossed on the outside of each cylinder head. See Figure 8-43.

Section 8

Disassembly

Figure 8-42. Removing Hydraulic Lifters.

Match Numbers

Figure 8-43. Match Numbers on Cylinder Barrel and Heads.

Disassemble Cylinder Heads

1. Remove the two hex flange screws, rocker arm pivots, and rocker arms from the cylinder head. See Figure 8-44.

Figure 8-45. Removing Valves with Valve Spring Compressor.

3. Once the valve spring is compressed, remove the following items. See Figures 8-46 and 8-47.

• Valve spring keepers

• Valve spring retainers

• Valve springs

• Valve spring caps

• Intake and exhaust valves (mark position)

• Valve stem seals

Figure 8-44. Removing Rocker Arms.

2. Compress the valve springs using a valve spring compressor. See Figure 8-45.

Figure 8-46. Valve Train Components.

Valve Stem Seals

Figure 8-47. Valve Stem Seals.

8.11

Section 8 Disassembly

NOTE: These engines use valve stem seals on

the intake and exhaust valves. Use a new seal whenever valves are removed, or if the seal is deteriorated in any way. Never reuse an old seal.

4. Repeat the above procedure for the other

cylinder head. Do not interchange parts from one cylinder head to the other.

Remove Breather Assembly

1. Remove the four fasteners securing the breather assembly, breather adapter (style based on spec), and gaskets to the crankcase.

2. Carefully break the gasket seals and remove all parts. Do not pry on the sealing surfaces as it could cause damage resulting in leaks. Note the assembly and orientation of parts. See Figures 8-48 and 8-49.

Breather

Remove Oil Reservoir and Pickup Screen

1. Remove the eight screws securing the oil reservoir and gasket to engine.

Figure 8-50. Removing Oil Reservoir.

2. Remove the mounting screw and carefully work the pickup screen off the end of the pickup tube. See Figure 8-51.

Breather Adapter

Figure 8-48. Removing Breather Assembly .

Breather Adapter (Certain Models)

Gasket

Pickup T ube

Pickup Screen

Mounting Screw

Figure 8-51. Removing Pickup Screen.

Figure 8-49. Removing Breather Adapter.

8.12

Section 8

Disassembly

Remove Closure Plate Assembly

1. Remove the fourteen hex flange screws securing the closure plate to the crankcase. See Figure 8-52.

Figure 8-52. Removing Closure Plate Screws.

2. Locate the two protruding tabs on the closure plate. Carefully tap to break the gasket seal. Do not pry on the sealing surfaces as this could cause leaks. Separate the closure plate from the crankcase. See Figure 8-53 and 8-54. Remove the old gasket.

Oil Pump Assembly

The oil pump is mounted to the inside of the closure plate. If service is required, refer to the service procedures under Oil Pump Assembly in Section 9.

Remove Camshaft

1. Remove the camshaft and shim (if used). See Figure 8-55.

Figure 8-55. Removing Camshaft.

Remove Connecting Rods with Pistons and Rings

1. Remove the two hex flange screws securing the closest connecting rod end cap. Remove the end cap. See Figure 8-56.

Tab

Figure 8-53. Location of T abs.

Figure 8-54. Removing Closure Plate.

Tab

Figure 8-56. Removing Connecting Rod Screws.

NOTE: If a carbon ridge is present at the top of

either cylinder bore, use a ridge reamer tool to remove the ridge before attempting to remove the piston.

8.13

Section 8 Disassembly

Figure 8-57. Remove Connecting Rod Caps.

NOTE: The cylinders are numbered on the

crankcase. Use the numbers to mark each end cap, connecting rod and piston for reassembly. Do not mix end caps and connecting rods.

2. Carefully remove the connecting rod and piston assembly from the cylinder bore. See Figure 8-58.

Figure 8-59. Removing Crankshaft.

Removal of Governor Gear Assembly

The governor gear is held onto the shaft by small molded tabs in the gear. When the gear is removed from the shaft, these tabs are destroyed and the gear must be replaced. Therefore, remove the gear only if absolutely necessary. If the governor cross shaft, yoke, or gear condition does not require removal, the governor gear may be left in place. If removal is necessary, perform as follows:

1. Remove the locking tab thrust washer and note orientation.

2. Using a screwdriver, carefully pry upward to unseat the governor gear assembly from the governor gear shaft. Remove the regulating pin and governor gear assembly. See Figure 8-60.

Governor Gear

Figure 8-58. Removing Piston/Connecting Rod Assemblies.

3. Repeat the above procedures for the other connecting rod and piston assembly.

Remove Crankshaft

1. Carefully pull the crankshaft from the crankcase. See Figure 8-59. Note thrust washers and shims if used.

8.14

Figure 8-60. Removing Governor Gear.

3. Inspect the governor gear shaft for wear or damage. Remove the shaft only if replacement is needed.

Section 8

Disassembly

Remove Governor Yoke, Cross Shaft, and Seal

1. Remove the two mounting screws securing the yoke to the governor cross shaft. See Figure 8-61.

Figure 8-61. Removing Cross Shaft/Y oke Screws.

2. Pull the governor cross shaft out of the crankcase and remove the seal.

Remove Lifter Feed Chamber Cover and Gaskets

1. Remove the three screws securing the lifter feed chamber baffle (some models only), cover, and gaskets. Carefully separate the parts from the crankcase. See Figure 8-62.

Remove Flywheel and PTO End Oil Seals

1. Remove the oil seals from the crankcase and closure plate using a seal puller. See Figure 8-63.

Figure 8-63. Removing Oil Seals.

Removal of Main Bearings

NOTE: Flywheel and PTO side main bearings

should only be removed if replacement is required due to wear. If removal is performed, use a press and support the casting surface around the bearing flange. Do not press against or support by the gasket/outer perimeter surface. See Figure 8-64.

Screws

Figure 8-62. Removing Lifter Feed Chamber Cover Components.

Baffle (Some Models Only)

Cover

Gasket

Support This Surface

Figure 8-64. Support Surface Details.

8.15

Inspection and Reconditioning

Section 9

Inspection and Reconditioning

Section 9

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 & External Governor, Section 5 Ignition, Charging, & 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. 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.

Use an aerosol gasket remover, paint stripper, or lacquer thinner to remove any old gasket material. Apply the solvent, allow time for it to work, and then brush the surface with a brass wire brush. After all old material is removed, clean the surface with isopropyl alcohol, lacquer thinner, or aerosol electrical contact cleaner. Do not scrape the surfaces, as any scratches, nicks, or burrs can result in leaks. See Service Bulletin 252 for further information.

Refer to A Guide to Engine Rebuilding (TP-2150-A) for additional information. Measurement Guide (TP-2159-B) and Engine Inspection Data Record (TP-2435) are also available; use these to record inspection results.

Camshaft

Inspection and Service

Check the lobes of the camshaft for wear or damage. See Section 1 for minimum lift and/or dimensional specifications. Inspect the cam gear for badly worn, chipped, or missing teeth. Replacement of the camshaft will be necessary if any of these conditions exist.

Crankshaft

Inspection and Service

Inspect the gear teeth of the crankshaft. If the teeth are badly worn, chipped, or some are missing, replacement of the crankshaft will be necessary.

Inspect the crankshaft bearing surfaces for scoring, grooving, etc. Replaceable bearings are used in the crankshaft bore of the closure plate and/or crankcase. Do not replace bearings unless they show signs of damage or are out of running clearance specifications. If the crankshaft turns easily, without noise, and there is no evidence of scoring, grooving, etc., on the races or bearing surfaces, the bearings can be reused.

Inspect the crankshaft keyways. If they are worn or chipped, replacement of the crankshaft will be necessary.

Inspect the crankpin for score marks or metallic pickup. Slight score marks can be cleaned with crocus cloth soaked in oil. If the wear limits, as stated in Specifications and Tolerances are exceeded, it will be necessary to either replace the crankshaft or regrind the crankpin to 0.25 mm (0.010 in.) undersize. If reground, a 0.25 mm (0.010 in.) undersize connecting rod (big end) must then be used to achieve proper running clearance. Measure the crankpin for size, taper, and out-of-round.

9.1

Section 9

Inspection and Reconditioning

NOTE: If the crankpin is reground, visually check to

ensure that the fillet blends smoothly with the crankpin surface. See Figure 9-1.

High Point from Fillet Intersections

The Fillet Must Blend Smoothly with the Bearing Journal Surface

45°

Minimum

This Fillet Area Must Be Completely Smooth

Figure 9-1. Crankpin Fillets.

The connecting rod journal can be ground one size under. When grinding a crankshaft, grinding stone deposits can get caught in the oil passages, which could cause severe engine damage. Removing the crankpin plug when the crankshaft is ground provides easy access for removing any grinding deposits that may collect in the oil passages.

Use the following procedure to remove and replace the plug.

Procedure to Install New Plug:

1. Use a single cylinder camshaft pin, Kohler Part

No. 47 380 09-S as a driver and tap the plug into the plug bore until it seats at the bottom of the bore. Make sure the plug is tapped in evenly to prevent leakage.

Crankcase

Inspection and Service

Check all gasket surfaces to make sure they are free of gasket fragments. Gasket surfaces must also be free of deep scratches or nicks.

Inspect the main bearing (if so equipped) for wear or damage (refer to Section 1, Specifications, Tolerances, and Special Torque Values). Replace the bearing or crankcase using a miniblock or short block as required.

Check the cylinder bore for scoring. In severe cases, unburned fuel can cause scuffing and scoring of the cylinder wall. It washes the necessary lubricating oils off the piston and cylinder wall. As raw fuel seeps down the cylinder wall, the piston rings make metal to metal contact with the wall. Scoring of the cylinder wall can also be caused by localized hot spots resulting from blocked cooling fins or from inadequate or contaminated lubrication.

Procedure to Remove Crankshaft Plug:

1. Drill a 3/16" hole through the plug in the crankshaft.

2. Thread a 3/4" or 1" long self-tapping screw with a flat washer into the drilled hole. The flat washer must be large enough to seat against the shoulder of the plug bore. See Figure 9-2.

Self-Tapping Screw

Flat Washer

234567

Plug

Crankshaft

Figure 9-2. Removing Crankpin Plug.

If the cylinder bore is badly scored, excessively worn, tapered, or out-of-round, resizing is necessary. Use an inside micrometer to determine the amount of wear (refer to the Specifications, Tolerances, and Special Torque Values, in Section 1), then select the nearest suitable oversize of either 0.25 mm (0.010 in.) or

0.50 mm (0.020 in.). Resizing to one of these oversizes will allow usage of the available oversize piston and ring assemblies. Initially, resize using a boring bar, then use the following procedures for honing the cylinder.

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 crankshaft crossbore. Honing is best accomplished at a drill speed of about 250 RPM and 60 strokes per minute. After installing coarse stones in hone, proceed as follows:

3. Tighten the self-tapping screw until it draws the plug out of the crankshaft.

9.2

Section 9

Inspection and Reconditioning

1. Lower hone into bore and after centering, adjust so the stones are in contact with the cylinder wall. Use of a commercial cutting-cooling agent is recommended.

2. With the lower edge of each stone positioned even with the lowest edge of the bore, start drill and honing process. Move the hone up and down while resizing to prevent the formation of cutting ridges. Check the size frequently.

NOTE: Kohler pistons are custom-machined to

exacting tolerances. When oversizing a cylinder, it should be machined exactly

0.25 mm (0.010 in.) or 0.50 mm (0.020 in.) over the new diameter (Section 1). The corresponding oversize Kohler replacement piston will then fit correctly.

3. When the bore is within 0.064 mm (0.0025 in.) of the desired size, remove the coarse stones and replace them with burnishing stones. Continue with the burnishing stones until the bore is within 0.013 mm (0.0005 in.) of the desired size and then use finish stones (220-280 grit) and polish the bore to its 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, and too steep an angle will result in high oil consumption. See Figure 9-3.

Clean Cylinder Bore After Honing

Proper cleaning of the cylinder walls following boring and/or honing is very critical to a successful overhaul. Machining grit left in the cylinder bore can destroy an engine in less than one hour of operation after 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.

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 often 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 11 mm (0.433 in.) above the bottom of the piston skirt and perpendicular to the piston pin. See Figure 9-4.

Figure 9-3. Cylinder Bore Crosshatch after Honing.

4. After resizing, 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 bottom. Two measurements should be taken (perpendicular to each other) at each of the three locations.

11 mm (0.433 in.)

Measure 11 mm above the Bottom of Piston Skirt at Right Angles to Piston Pin

Figure 9-4. Measuring Piston Diameter.

9.3

Section 9 Inspection and Reconditioning

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 difference between the bore diameter and the piston diameter (step 2 minus step 1).

Flywheel

Inspection

Inspect the flywheel for cracks and the flywheel keyway for damage. Replace the flywheel if it is cracked. Replace the flywheel, the crankshaft, and the key if flywheel key is sheared or the keyway is damaged.

Inspect the ring gear for cracks or damage. Kohler does not provide the ring gear as a serviceable part. Replace the flywheel if the ring gear is damaged.

Cylinder Head and Valves

Inspection and Service

After cleaning, check the flatness of the cylinder head and the corresponding top surface of the crankcase, using a surface plate or piece of glass and feeler gauge as shown in Figure 9-5. The maximum allowable out of flatness is 0.076 mm (0.003 in.).

Feeler Gauge

Figure 9-5. Checking Cylinder Head Flatness.

Carefully inspect the valve mechanism parts. Inspect the valve springs and related hardware for excessive wear or distortion. Check the valves and valve seat area or inserts for evidence of deep pitting, cracks, or distortion. Check clearance of the valve stems in the guides. See Figure 9-6 for valve details and specifications.

9.4

Section 9

Inspection and Reconditioning

EXHAUST V ALVE

Dimension

Seat Angle

Seat Taper

Guide Depth

Guide I.D.

Valve Head Diameter

Valve Face Angle

Valve Margin (Min.)

Valve Stem Diameter

INT AKE VAL VE

INT

EXH

Intake

89° 30°

8.5 mm (0.334 in.)

7.038/7.058 mm (0.2771/0.2779 in.)

38.625/38.685 mm (1.5206/1.5230 in.) 45°

1.0 mm (0.0393 in.)

6.982/7.000 mm (0.2749/0.2756 in.)

89° 30°

8.5 mm (0.334 in.)

7.038/7.058 mm (0.2771/0.2779 in.)

31.625/31.825 mm (1.2450/1.2549 in.) 45°

1.0 mm (0.0393 in.)

6.970/6.988 mm (0.2744/0.2751 in.)

Exhaust

Figure 9-6. Valve Details.

Hard starting or loss of power accompanied by high fuel consumption may be symptoms of faulty valves. Although these symptoms could also be attributed to worn rings, remove and check the valves first. After removal, clean the valve heads, faces, and stems with a power wire brush.

Then, carefully inspect each valve for defects such as a warped head, excessive corrosion, or a 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.

9.5

Section 9 Inspection and Reconditioning

Normal: Even after 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 attributed to excessive hours or a combination of poor operating conditions.

Leakage: A poor grind on face or seat of valve will allow leakage resulting in a burned valve 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 after cleaning.

9.6

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.

Gum: Gum deposits usually result from using stale gasoline. 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.

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.

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.

9.7

Section 9 Inspection and Reconditioning

Valve Guides

If a valve guide is worn beyond specifications, it will not guide the valve in a straight line. This may result in burnt 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 of the guide. 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 by subtracting the stem diameter from the guide diameter. 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.

The maximum (I.D.) wear on the intake valve guide is

7.135 mm (0.2809 in.) while 7.159 mm (0.2819 in.) is the maximum allowed on the exhaust guide. The guides are not removable but can be reamed 0.25 mm (0.010 in.) oversize. Valves with 0.25 mm oversize stems must then be used.

If the guides are within limits but the valve stems are worn beyond limits, install new valves.

Valve Seat Inserts

Hardened steel alloy intake and exhaust valve seat inserts are press fitted into the cylinder head. The inserts are not replaceable but can be reconditioned if not too badly pitted or distorted. If cracked or badly warped, the cylinder head should be replaced.

Recondition the valve seat inserts following the instructions provided with the valve seat cutter being used. A typical cutter is shown in Figure 9-7. The final cut should be made with an 89° cutter as specified for the valve seat angle in Figure 9-6. Cutting the proper 45° valve face angle as specified in Figure 9-6, and the proper valve seat angle (44.5°, half of the full 89° angle), will achieve the desired 0.5° (1.0° full cut) interference angle where the maximum pressure occurs on the outside diameters of the valve face and seat.

Valve Seat Cutter

Pilot

Figure 9-7. Typical Valve Seat Cutter.

Lapping Valves

Reground or new valves must be lapped in, to provide proper fit. Use a hand valve grinder with a suction cup for final lapping. Lightly coat the valve face with a fine grade of grinding compound, then rotate the valve on its seat with the grinder. Continue grinding until a smooth surface is obtained on the seat and on the valve face. Thoroughly clean the cylinder head in soap and hot water to remove all traces of grinding compound. After drying the cylinder head, apply a light coating of SAE 10 oil to prevent rusting.

Valve Stem Seals

These engines use valve stem seals on the intake and exhaust valves. Always use new seals when the valves are removed from the cylinder head. The seals should also be replaced if deteriorated or damaged in any way. Never reuse an old seal.

Pistons and Rings

Inspection

Scuffing and scoring of pistons and cylinder walls occurs when internal engine temperatures approach the welding point of the piston. Temperatures high enough to do this are created by friction, which is usually attributed to improper lubrication and/or overheating of the engine.

Normally, very little wear takes place in the piston boss-piston pin area. If the original piston and connecting rod can be reused after new rings are installed, the original pin can also be reused but new piston pin retainers are required. The piston pin is included as part of the piston assembly – if the pin boss in the piston or the pin are worn or damaged, a new piston assembly is required.

9.8

Section 9

Inspection and Reconditioning

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.

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 after ignition. This creates two flame fronts which 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 often more severe than detonation damage. Preignition is caused by a hot spot in the combustion chamber from sources such as glowing carbon deposits, blocked cooling fins, an improperly seated valve, or wrong spark plug(s).

See Figure 9-8 for some common types of piston and ring damage.

Overheated or Deteriorated Oil

Figure 9-8. Common Types of Piston and Ring Damage.

Abrasive Scratched RingsStuck, Broken Rings

Scored Piston and Rings

9.9

Section 9 Inspection and Reconditioning

Replacement pistons are available in STD bore size, and in 0.25 mm (0.010 in.), and 0.50 mm (0.020 in.) oversize. Replacement pistons include new piston ring sets and new piston pins.

Replacement ring sets are also available separately for STD, 0.25 mm (0.010 in.), and 0.50 mm (0.020 in.) oversize pistons. Always use new piston rings when installing pistons. Never reuse old rings.

Some important points to remember when servicing piston rings:

1. The cylinder bore must be deglazed before service ring sets are used.

2. If the cylinder bore does not need reboring and if the old piston is within wear limits and free of score or scuff marks, the old piston may be reused.

3. Remove the old rings and clean up the grooves. Never reuse old rings.

4. Before installing the new rings on the piston, place the top two rings, each in turn, in its running area in the cylinder bore and check the end gap. See Figure 9-9. Compare the ring gap to the specifications listed in Section 1.

Figure 9-10. Measuring Piston Ring Side Clearance.

Install New Piston Rings

To install new 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. See Figure 9-11. Install the bottom (oil control) ring first and the top compression ring last. Refer to Figure 9-12.

Piston Ring

Figure 9-9. Measuring Piston Ring End Gap.

5. After installing the new compression (top and middle) rings on the piston, check the piston-toring side clearance. Compare the clearance to specifications listed in Section 1. If the side clearance is greater than specified, a new piston must be used. Refer to Figure 9-10.

9.10

Piston Ring Expander

Figure 9-11. Inst alling Piston Rings.

Section 9

Inspection and Reconditioning

Piston Ring

End Gap

Identification Mark

Piston

T op Compression Ring

Center Compression Ring

Rails

Oil Control Ring (Three Piece)

Figure 9-12. Piston Ring Installation.

1. Oil Control Ring (Bottom Groove): Install the expander and then the rails. Make sure the ends of expander are not overlapped.

Expander

Service replacement connecting rods are available in STD crankpin size and 0.25 mm (0.010 in.) undersize. Always refer to the appropriate parts information to ensure that correct replacements are used.

Hydraulic Lifters

Inspection

Check the base surface of the hydraulic lifters for wear or damage. If the lifters need to be replaced, apply a liberal coating of Kohler lubricant (see Section 2) to the base of each new lifter before it is installed.

“Bleeding” the Lifters

To prevent a possible bent push rod or broken rocker arm, it is important to “bleed” any excess oil out of the lifters before they are installed.

1. Cut a 50-75 mm (2-3 in.) piece from the end of an old push rod and chuck it in a drill press.

2. Lay a rag or shop towel on the table of the drill press and place the lifter, open end up, on the towel.

3. Lower the chucked push rod until it contacts the plunger in the lifter. Slowly “pump” the plunger two or three times to force the oil out of the feed hole in the side of the lifter.

2. Middle Compression Ring (Center Groove): Install the center ring using a piston ring installation tool. Make sure the identification mark is up or the dykem stripe (if contained), is to the left of the end gap.

3. Top Compression Ring (Top Groove): Install the top ring using a piston ring expander. Make sure the identification mark is up or the dykem stripe (if contained), is to the left of the end gap.

Connecting Rods

Offset, stepped-cap connecting rods are used in these engines.

Inspection and Service

Check the bearing area (big end) for excessive wear, score marks, running and side clearances (refer to Section 1, Specifications, Tolerances, and Special Torque Values). Replace the rod and cap if scored or excessively worn.

Governor Gear Assembly

Inspection

The governor gear is located within the crankcase. Inspect the governor gear teeth. Replace the gear if it is worn, chipped, or if any teeth are missing. Inspect the governor weights. They should move freely in the governor gear.

Disassembly

The governor gear must be replaced once it is removed from the crankcase.

NOTE: The governor gear is held onto the shaft by

small molded tabs in the gear. When the gear is removed from the shaft these tabs are destroyed and the gear must be replaced. Therefore, remove the gear only if absolutely necessary.

9.11

Section 9 Inspection and Reconditioning

Closure Plate Assembly

Inspection

Inspect the oil seal in the closure plate and remove it if it is worn or damaged. Refer to Install Closure Plate Oil Seal in Section 10 for new oil seal installation.

Inspect the main bearing surface for wear or damage (refer to Section 1, Specifications, Tolerances, and Special Torque Values). Replace the bearing or closure plate assembly if required.

Oil Pump Assembly

Disassembly

1. Remove the three hex flange screws securing the oil pump housing including the relief valve baffle, and the single screw with clamp for the pickup tube. See Figure 9-13.

2. Remove the oil pump housing and pickup tube from the closure plate.

3. Remove the oil pump gerotor gears from the closure plate recess.

Inspection

Inspect the oil pump housing, gerotor gears, and closure plate recess for nicks, burrs, wear, or any visible damage. Inspect the inlet seal for the pickup tube in the housing. If any parts are worn or damaged, replace the seal, oil pump or closure plate as required.

Reassembly

1. Make sure the recess in the closure plate for the oil pump gerotor gears is clean.

2. Lubricate the oil pump gerotor gears with grease (Lubriplate the recess. See Figure 9-14.

100 or equivalent), and install into

4. Remove the oil pickup by pulling it free from the oil pump body.

5. The relief valve is a one-piece style, staked to the oil pump housing; removal should not be attempted, nor is internal servicing possible. If a problem with the relief valve is encountered, the oil pump should be replaced. See Figure 9-15.

Mounting Screws

Oil Pump

Pickup Tube

Figure 9-13. Removing Oil Pump.

Relief Valve Baffle

Figure 9-14. Installing and Lubricating Oil Pump Gerotor Gears.

3. Lightly lubricate with oil and install the inlet seal into the oil pump housing until it is fully seated. See Figure 9-15.

Inlet Seal

Relief Valve

9.12

Figure 9-15. Installing Inlet Seal in Oil Pump Housing.

Section 9

Inspection and Reconditioning

4. Install the O-Ring in the groove of the oil pump housing. Use a small quantity of grease to hold it in place. See Figure 9-16.

O-Ring

Figure 9-16. O-Ring Installed in Oil Pump Housing.

5. Lightly lubricate the I.D. of the inlet seal with oil and carefully insert the ferruled end of the pickup tube through the grommet, into the oil pump housing. Position the pickup tube so the outboard end faces up. See Figure 9-17.

7. Install the clamp for the pickup tube and finger tighten the screw. Check the alignment of the parts and torque the oil pump housing screws as specified using the sequence shown in Figure 9-18.

Torque the hex flange screws as follows:

a. Install fastener into location No. 1 and

lightly tighten to position the pump.

b. Install fastener into location No. 2 and

fully torque to the recommended value.

c. Install fastener into location No. 3 and

fully torque to the recommended value.

d. Finish torquing fastener in location No. 1

to the recommended value.

First Time Installation: 10.7 N·m (95 in. lb.) All Reinstallations: 6.7 N·m (60 in. lb.)

6. Install the oil pump housing with the pickup tube, over the oil pump boss and gears. Position the relief valve baffle on screws 2 and 3. See Figure 9-18. Align the three screw hole locations.

Mounting Screws

Oil Pump

Pickup Tube

Figure 9-17. Installed Oil Pump and Pickup Tube.

Relief Valve Baffle

Pickup Tube Clamp and Screw

Figure 9-18. Oil Pump Screws Torque Sequence.

8. Torque the clamp (pickup tube) mounting screw

to 10.7 N·m (95 in. lb.) into a new hole, or 7.3 N·m (65 in. lb.) into a used hole. See Figure 9-17.

9.13

Section 10

Reassembly

Section 10

Reassembly

General

NOTE: Make sure the engine is assembled using all

specified torque values, tightening sequences, and clearances. Failure to observe specifications could cause severe engine wear or damage. Always use new gaskets. Apply a small amount of oil to the threads of critical fasteners before assembly, unless a Sealant or Loctite® is specified or preapplied.

Make sure all traces of any cleaner are removed before the engine is assembled and placed into operation. Even small amounts of these cleaners can quickly break down the lubricating properties of engine oil.

Check the closure plate, crankcase, cylinder heads, and valve covers to be certain that all of the old gasket material has been removed. Use gasket remover, lacquer thinner, or paint remover to remove any remaining traces. Clean the surfaces with isopropyl alcohol, acetone, lacquer thinner, or electrical contact cleaner.

Typical Reassembly Sequence

The following sequence is suggested for complete engine reassembly. This procedure assumes that all components are new or have been reconditioned, and all component subassembly work has been completed. The sequence may vary to accommodate options or special equipment. Detailed procedures follow:

16. Install push rods and rocker arms.

17. Install valve covers.

18. Install spark plugs.

19. Install oil filter adapter.

20. Install intake manifold.

21. Install oil filter housing assembly.

22. Install backing shroud assembly.

23. Install stator, wiring harness, and rectifierregulator.

24. Install flywheel.

25. Install ignition modules.

26. Install outer cylinder baffles.

27. Install oil cooler.

28. Install cooling fan and grass screen.

29. Install electric starter.

30. Install valley baffles.

31. Install carburetor

32. Install governor lever.

33. Install control bracket and air cleaner assembly.

34. Install throttle and choke linkages.

35. Install Oil Sentry™switch (if equipped).

36. Install blower housing and cylinder shrouds.

37. Install control panel (if equipped).

38. Install muffler.

39. Install oil filter and add oil to crankcase.

40. Connect spark plug leads.

Install Flywheel End Oil Seal

1. Make sure that the seal bore of the crankcase is clean and free of any nicks or burrs. See Figure 10-1.

1. Install flywheel end oil seal.

2. Install lifter feed chamber gaskets and cover.

3. Install flywheel end main bearing.

4. Install governor shafts, seal, and governor gear.

5. Install crankshaft.

6. Install connecting rods with pistons and rings.

7. Install camshaft.

8. Install closure plate main bearing and oil seal.

9. Install closure plate assembly.

10. Install oil pickup screen.

11. Install oil reservoir.

12. Check crankshaft end play.

13. Install breather assembly.

14. Install hydraulic lifters.

15. Assemble and install cylinder heads.

Figure 10-1. Seal Bore of Crankcase.

10.1

Section 10 Reassembly

2. Apply a light coat of clean engine oil to the outside diameter of the oil seal.

3. Install the oil seal into the crankcase using a seal driver. Make sure the oil seal is installed straight and true in the bore and that the tool bottoms against the crankcase. See Figures 10-2 and 10-3.

Figure 10-2. Installing Oil Seal with Driver.

Mounting Screws

Baffle (Used on Some Models Only)

Lifter Feed Chamber

Figure 10-4. Lifter Feed Chamber Assembly Details.

Cover

Gasket

Install Flywheel End Main Bearing

If the flywheel end main bearing was removed in servicing, install a new bearing using an arbor press and driver.

1. Make sure the crankcase bore for the main bearing is clean, dry and free of nicks or burrs.

Figure 10-3. Installed Flywheel End Oil Seal.

Install Lifter Feed Chamber Gaskets and Cover

1. Install the lifter feed chamber gasket, followed by the lifter feed cover over the lifter feed chamber. If used, position the breather baffle on top of the parts with the winged offset down.

2. Install the three screws. Make sure all the parts are properly aligned. Torque the screws to 6.2

N·m (55 in. lb.) into new holes, or 4.0 N·m (35 in. lb.), into used holes. See Figure 10-4.

2. Press the flywheel side main bearing in place with the notch oriented in the 12 o’clock position using an arbor press and driver. See Figure 10-5. Make sure the bearing is fully seated against the flange and the oil feed hole is open in the crankcase. See Figure 10-6.

3. Apply a light coat of clean engine oil to the inner surface of the main bearing.

Figure 10-5. Installing Main Bearing.

10.2

Notch

Main Bearing

Figure 10-6. Installed Main Bearing.

Install Governor Shafts, Seal, and Governor Gear

If the governor shafts, seal, and/or governor gear were removed, reassemble as follows.

Section 10

Reassembly

2. If the governor gear shaft was removed, press or lightly tap the replacement shaft into the closure plate to depth shown in Figure 10-10.

Governor Gear Shaft

Figure 10-9. Installed Governor Gear Shaft.

1. Lightly oil the lip and outside diameter of the new governor cross shaft seal. Install the seal into the crankcase to the depth shown in Figure 10-8.

Seal

Figure 10-7. Installing Governor Cross Shaft Seal.

Seal depth

1.5-2.0 mm (0.059-0.078 in.)

12.66 mm (0.498 in.)

Crankcase Surface

Figure 10-10. Governor Gear Shaft Press Depth.

3. Lubricate the governor cross shaft bearing surfaces in the crankcase with engine oil. Insert the end with the flat for the governor gear yoke into the crankcase first and position so the flat is up. See Figure 10-11.

Governor Cross Shaft

Governor Gear Shaft

Crankcase Surface

Oil Seal

Figure 10-8. Governor Shaft Seal Depth.

Figure 10-11. Inst alling Governor Cross Shaft.

10.3

Section 10 Reassembly

4. Attach the governor yoke to the cross shaft so the

curved section is up as marked. Secure with the two screws. If a thread locking compound is not preapplied, apply a small amount of Loctite No. 266 or equivalent, to the screw threads before installing. Torque the screws to 2.2 N·m (20 in. lb.). See Figure 10-12.

Governor Gear Assembly

Figure 10-14. Installing Governor Gear Assembly .

Figure 10-12. Installed Governor Yoke.

5. Install the first regulating pin with the head down so it will contact the yoke. Install the governor gear with the second regulating pin and the flyweight assembly in/down onto the governor shaft until it locks into position. Apply a small amount of grease to the locking tab thrust washer and install on top of the governor gear so the tang is facing up in the 6 o’clock position. See Figures 10-13, 10-14, and 10-15.

Second Regulating Pin

Governor Gear

First Regulating Pin

Figure 10-13. Regulating Pins and Governor Gear.

Tab Position

Figure 10-15. Installed Locking Tab Washer.

Install Crankshaft

1. Carefully slide the flywheel end of the crankshaft through the main bearing in the crankcase. See Figure 10-16.

10.4

Figure 10-16. Installing Crankshaft.

Install Connecting Rods with Pistons and Rings

NOTE: The cylinders are numbered on the

crankcase. Make sure to install the piston, connecting rod and end cap into the appropriate cylinder bore as previously marked at disassembly. Do not mix the end caps and connecting rods.

NOTE: Proper orientation of the piston/connecting

rod assemblies inside the engine is extremely important. Improper orientation can cause extensive wear or damage. Be certain the pistons and connecting rods are assembled exactly as shown in Figure 10-17.

Section 10

Reassembly

Figure 10-18. FL Y Mark on Piston.

No. 1 Side

Figure 10-17. Piston and Connecting Rod Orientation.

1. Stagger the piston rings in the grooves until the end gaps are 120° apart. The oil ring rails should also be staggered.

2. Lubricate the cylinder bore, piston, and piston rings with engine oil. Compress the rings of the #1 piston using a piston ring compressor.

3. Lubricate the crankshaft journals and connecting rod bearing surfaces with engine oil.

4. Make sure the FLY stamping on the piston is facing toward the flywheel side of the engine. See Figure 10-18. Use a hammer with a rubber grip and gently tap the piston into the cylinder as shown in Figure 10-19. Be careful that the oil ring rails do not spring free between the bottom of the ring compressor and top of the cylinder.

No. 2 Side

Figure 10-19. Installing Piston Assembly Using Ring Compressor T ool.

5. Install the inner rod cap to the connecting rod using the two hex flange screws. Torque the screws in increments to 11.3 N·m (100 in. lb.). Illustrated instructions are provided in the service rod package. See Figure 10-20.

NOTE: Align the chamfer of the connecting rod

with the chamfer of its mating end cap. When installed, the flat faces of the connecting rods should face each other. The faces with the raised rib should be toward the outside.

Figure 10-20. T orquing Connecting Rod End Cap Screws.

10.5

Kohler CH980, CH960, CH1000, CH940 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

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