Kohler LH640, LH775, LH755, LH690 User Manual

SERVICE MANUAL

AEGIS

LIQUID-COOLED HORIZONTAL CRANKSHAFT

LH630-775

™

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

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

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

Section 4. Air Cleaner System.................................................................................................

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

Section 5B. Electronic Fuel Injection (EFI) Fuel System ......................................................

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

Section 7. Cooling System ......................................................................................................

Section 8. Electrical System and Components .....................................................................

Section 9. Disassembly ...........................................................................................................

Section 10. Inspection and Reconditioning ...........................................................................

Section 11. Reassembly...........................................................................................................

Safety and General Information

Section 1

Safety and General Information

Safety Precautions

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

WARNING

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

CAUTION

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

Section 1

NOTE

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

For 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 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.

WARNING

Rotating Parts can cause severe injury.

Stay away while engine is in operation.

Rotating Part s!

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.

WARNING

Hot liquid can cause severe burns.

Do not loosen radiator cap while engine is operating or warm to the touch.

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.

1.2

Hot Liquid!

The liquid coolant can get extremely hot from operation. Turning the radiator cap when the engine is hot can allow steam and scalding liquid to blow out and burn you severely.

Shut off machine. Only remove radiator cap when cool enough to touch with bare hands. Slowly loosen cap to first stop to relieve pressure before removing completely.

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.

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. The primary location is on the side of the flywheel cover. See Figure 1-1. Placement may vary due to OEM requirements and specific options involved. 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.

Liquid Cooled Horizontal Crankshaft Numerical Designation

B. Spec. No.

Model

LH630-0001 LH640-0001 LH685-0001 LH690-0001

LH750-0001 LH755-0001 LH760-0001 LH775-0001

C. Serial No.

Year Manufactured Code

Code Year

31 2001 32 2002 33 2003 34 2004 35 2005 36 2006 37 2007

Figure 1-2. Explanation of Engine Identification Numbers.

L H 685 S

Version Code

S = Electric Start

LH685-0001

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

31 05810334

Factory Code

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. Failure to use the correct oil, or using dirty oil, causes premature engine wear and failure.

Oil T ype

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.

*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.

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

Coolant Recommendations

Use equal parts of ethylene glycol and water only. Distilled or deionized water is recommended, especially in areas where the water contains a high mineral content. Propylene glycol based antifreeze is not recommended.

This mixture will provide protection from -37°C (-34°F) to 108°C (226°F). For protection and use outside the indicated temperature limits, follow the antifreeze manufacturer's instructions on the container, but do not exceed 70% antifreeze.

DO NOT use antifreeze with stop-leak additive(s), or put any other additives in the cooling system.

Fuel Recommendations

WARNING: Explosive Fuel!

NOTE: Synthetic oils meeting the listed

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

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

Figure 1-3. Oil Container Logo.

1.4

General Recommendations

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

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

Do not add oil to the gasoline.

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

Fuel Type

For best results, use only clean, fresh, unleaded gasoline with a pump sticker octane rating of 87 or higher. In countries using the Research method, it should be 90 octane minimum.

Section 1

Safety and General Information

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 are not approved.

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

WARNING: Accident al 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.

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

Every 100 Hours

Annually or

Every 200 Hours Every 250 Hours

Annually or

Every 500 Hours

Every 2 Y ears or

Every 1000 Hours Every 1500 Hours

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

Maintenance Required

• Fill fuel tank.

• Check oil level.

• Check coolant level.

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

• Check the screen, radiator, and cooling areas, clean as necessary1.

• Clean and check cooling areas1.

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

• Check spark plug condition and gap.

• Change fuel filter (carbureted models).

• Replace spark plugs.

• Change engine coolant.

• Replace fuel filter1 (EFI engines).

Refer to:

Section 5 Section 6 Section 7 Section 4 Section 7

Section 7

Section 6 Section 5 Section 8

Section 4• Replace air cleaner element and check inner element1.

Section 8

Section 7

Section 5B

1.5

Section 1 Safety and General Information

Storage

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

1. Clean the exterior surfaces of the radiator and engine. On EFI engines, avoid spraying water at the wiring harness or any of the electrical components.

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

3. The coolant (anti-freeze) mixture should be in good condition and tested to guard against freezing in cold temperatures. The recommended 50/50 mixture will normally provide protection down to temperatures of -37°C (-34°F). If storage temperatures will fall below this, the cooling system should be drained completely. A note should then be attached to the equipment and/or engine as a reminder to refill the cooling system before starting.

4. 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 manufacturers recommendations, and add the correct amount for the capacity of the fuel system. Fill the fuel tank with clean, fresh gasoline. Run the engine for 2-3 minutes to get stabilized fuel into the carburetor. Close fuel shut-off valve when unit is being stored or transported.

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

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

6. On units with EFI engines, disconnect the negative (-) battery cable or use a "battery minder" trickle charger while the unit is in storage.

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

1.6

Section 1

Safety and General Information

Fuel Pump

Rain Cap Removal

(0.906)

Mounting Hole

Flywheel End

440.00

(17.323)

2X 184.20

(7.252)

458.49

(18.051)

Overall

Mounting Hole

127.90 (5.035)

622.54

(24.509)

Overall without Rain Cap

673.70

(26.524)

Overall

Optional Oil Fill

152.08

(5.987)

PTO Side

Oil

Drain

143.25 (5.640)

38.00

(1.496)

175.41 (6.906)

Mounting Hole "A"

Oil Filter Side

119.78

Fill

431.61

(16.992)

(4.716)

39.00 (1.535) Oil Fill

89.00 (3.504) Mounting Holes

Mounting Hole "A"

Starter Side

Air Intake Optional Orientation

583.30

(22.965)

490.74

(19.320)

Center of Air Intake

Engine Mounting Surface

120.96 (4.762)

Coolant

Overflow

38.00

(1.496) C

Oil Drain Plug

238.61

(9.394)

Figure 1-4. T ypical Engine Dimensions.

2X 297.47

(1.711)

Exhaust Ports

101.60 (4.000) Option

112.92 (4.446)

4.00

(.157)

Mounting Surface

Pilot

155.58 (6.125)

4X 45°

50.99

(2.007)

Mounting Hole "A"

1/4 Inch Square Key

5/8-18 UNF Thread

7/16-20 Thread Option

36.50

(1.437)

2X 60°

2X 45°

4X 3/8-16 UNC-2B Inch

Oil Filter

299.00 (11.77)

235.19 (9.259)

28.575

Option

(1.125)

142.88 Bolt Circle (5.625)

15.70 Oil Filter Removal (0.618)

Bolt Circle 197.00

4x 7/16-14 UNC-2B Inch

177.80 Pilot (7.000)

(7.756)

Top View

Dimensions in millimeters. Inch equivalents shown in ().

1.7

Section 1 Safety and General Information

General Specifications

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

LH630 ................................................................................................................ Maximum ............... 16.4 kW (22 HP)

Recommended ...... 13.9 kW (18.7 HP)

LH640 ................................................................................................................ Maximum ............... 17.9 kW (24 HP)

Recommended ...... 15.2 kW (20.4 HP)

LH685 ................................................................................................................ Maximum ............... 18.6 kW (25 HP)

Recommended ...... 15.9 kW (21.3 HP)

LH690 ................................................................................................................ Maximum ............... 19.4 kW (26 HP)

Recommended ...... 16.5 kW (22.1 HP)

LH750 ................................................................................................................ Maximum ............... 20.1 kW (27 HP)

Recommended ...... 17.1 kW (22.9 HP)

LH755 ................................................................................................................ Maximum ............... 20.9 kW (28 HP)

Recommended ...... 17.7 kW (23.8 HP)

LH760 ................................................................................................................ Maximum ............... 21.6 kW (29 HP)

Recommended ...... 18.4 kW (24.7 HP)

LH775 ................................................................................................................ Maximum ............... 23.1 kW (31 HP)

Recommended ...... 19.7 kW (26.4 HP)

Peak Torque

LH630 @ 2200 RPM ...................................................................................................................... 48.0 N·m (35.4 ft. lb.)

LH640 @ 2400 RPM ...................................................................................................................... 51.9 N·m (38.3 ft. lb.)

LH685 @ 2200 RPM ...................................................................................................................... 54.3 N·m (40.1 ft. lb.)

LH690 @ 2400 RPM ...................................................................................................................... 58.1 N·m (42.9 ft. lb.)

LH750 @ 2200 RPM ...................................................................................................................... 61.0 N·m (45 ft. lb.)

LH755 @ 2800 RPM ...................................................................................................................... 61.5 N·m (45.4 ft. lb.)

LH760 @ 2600 RPM ...................................................................................................................... 61.7 N·m (45.5 ft. lb.)

LH775 @ 2400 RPM ...................................................................................................................... 64.6 N·m (47.7 ft. lb.)

Bore

LH630,LH640 ................................................................................................................................ 77 mm (3.03 in.)

LH685,LH690 ................................................................................................................................ 80 mm (3.15 in.)

LH750,LH755,LH760,LH775 ....................................................................................................... 83 mm (3.3 in.)

Stroke

LH630,LH640,LH685,LH690 ....................................................................................................... 67 mm (2.64 in.)

LH750,LH755,LH760,LH775 ....................................................................................................... 69 mm (2.7 in.)

Displacement

LH630,LH640 ................................................................................................................................ 624 cc (38.1 cu. in.)

LH685,LH690 ................................................................................................................................ 674 cc (41.1 cu. in.)

LH750,LH755,LH760,LH775 ....................................................................................................... 747 cc (45.6 cu. in.)

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

to assembly.

NOTE: All listed dimensions and tolerances are measured at 20°C (68°F).

1.8

Section 1

Safety and General Information

General Specifications1cont.

Compression Ratio

LH630,LH640,LH685,LH690 ............................................................................ 8.5:1

LH750,LH755,LH760,LH775 ............................................................................ 8.7:1

Dry Weight

LH630,LH640,LH685,LH690,LH755 ............................................................... 51.7 kg (114 lb.)

LH760,LH775 ..................................................................................................... 52.6 kg (116 lb.)

Oil Capacity (w/filter) - approximate,

determined by oil filter used: .................................................................................. 1.6-1.8 L (1.7-1.9 U.S. qt.)

Coolant Capacity (equal parts of water and ethylene glycol) ............................ 2.0 L (2.18 U.S. qt.)

Angle of Operation - Maximum (At Full Oil Level) All Directions .................. 20°

Camshaft

End Play (With Shim)............................................................................................... 0.076/0.127 mm (0.0030/0.0050 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.)

Carburetor and Intake Manifold

Intake Manifold Fastener Torque (torque in 2 increments) ................................ first to 7.4 N·m (66 in. lb.)

finally to 9.9 N·m (88 in. lb.)

Thermostat Housing Mounting Fastener Torque ................................................. 6.2-7.3 N·m (55-65 in. lb.)

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

Connecting Rod

Cap Fastener Torque (torque in increments) ........................................................ 11.3 N·m (100 in. lb.)

Connecting Rod-to-Crankpin Running Clearance

New ..................................................................................................................... 0.043/0.068 mm (0.0016/0.0026 in.)

Max. Wear Limit ................................................................................................ 0.083 mm (0.0032 in.)

Connecting Rod-to-Crankpin Side Clearance ...................................................... 0.26/0.63 mm (0.0102/0.0248 in.)

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

Piston Pin End I.D.

New ..................................................................................................................... 17.015/17.023 mm (0.6699/0.6702 in.)

Max. Wear Limit ................................................................................................ 17.036 mm (0.6707 in.)

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

to assembly.

1.9

Section 1 Safety and General Information

Crankcase

Governor Cross Shaft Bore I.D.

New .............................................................................................................. 8.025/8.075 mm (0.3159/0.3179 in.)

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

Breather Cover Fastener Torque ...................................................................... 10.7 N·m (95 in. lb.) into new hole

7.3 N·m (65 in. lb.) into used hole

Oil Drain Plug Torque ....................................................................................... 13.6 N·m (10 ft. lb.)

Closure Plate

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

Crankshaft

End Play (free) .................................................................................................... 0.070/0.590 mm (0.0028/0.0230 in.)

Crankshaft Sleeve Bearing I.D. (crankcase)

New .............................................................................................................. 40.974/40.987 mm (1.6131/1.6136 in.)

Max. Wear Limit ......................................................................................... 41.000 mm (1.6141 in.)

Crankshaft Bore (in closure plate)

New .............................................................................................................. 40.974/41.000 mm (1.6131/1.6141 in.)

Max. Wear Limit ......................................................................................... 41.038 mm (1.6156 in.)

Crankshaft Bore (in closure plate)-to-Crankshaft

Running Clearance - New ......................................................................... 0.039/0.087 mm (0.0015/0.0034 in.)

Main Bearing Journals

O.D. - New ................................................................................................... 40.913/40.935 mm (1.6107/1.6116 in.)

O.D. - Max. Wear Limit.............................................................................. 40.84 mm (1.608 in.)

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

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

Crankshaft to Sleeve Bearing (crankcase)

Running Clearance - New ......................................................................... 0.039/0.074 mm (0.0015/0.0029 in.)

Connecting Rod Journal

O.D. - New ................................................................................................... 35.955/35.973 mm (1.4156/1.4163 in.)

O.D. - Max. Wear Limit.............................................................................. 35.94 mm (1.415 in.)

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

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

Crankshaft T.I.R.

PTO End, Crank in Engine ........................................................................ 0.15 mm (0.0059 in.)

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

Cylinder Bore

Cylinder Bore I.D.

New

LH630,LH640 ........................................................................................... 77.000/77.025 mm (3.0315/3.0325 in.)

LH685,LH690 ........................................................................................... 80.000/80.025 mm (3.1496/3.1506 in.)

LH750,LH755,LH760,LH775 ................................................................. 83.006/83.031 mm (3.2679/3.2689 in.)

1.10

Section 1

Safety and General Information

Cylinder Bore cont.

Max. Wear Limit

LH630,LH640 .......................................................................................................77.063 mm (3.0340 in.)

LH685,LH690 .......................................................................................................80.065 mm (3.1522 in.)

LH750,LH755,LH760,LH775 .............................................................................83.069 mm (3.2704 in.)

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

Max. Taper ............................................................................................................... 0.05 mm (0.0020 in.)

Cylinder Head

Cylinder Head Fastener Torque (torque in 2 increments) .......................................first to 16.9 N·m (150 in. lb.)

finally to 33.9 N·m (300 in. lb.)

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

Rocker Pivot Fastener Torque ...................................................................................... 11.3 N·m (100 in. lb.)

Electric Starter

Starter Thru Bolt Torque ............................................................................................... 5.6-9.0 N·m (49-79 in. lb.)

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

Starter Brush Holder Fastener Torque ........................................................................ 2.5-3.3 N·m (22-29 in. lb.)

Starter Solenoid Fastener Torque ................................................................................ 4.0-6.0 N·m (35-53 in. lb.)

Starter Solenoid Positive (+) Brush Lead Retaining Nut Torque ............................ 8.0-11.0 N·m (71-97 in. lb.)

Fan/Flywheel

Rear Fan Shaft to Mounting Bracket Nut Torque ......................................................15.8 N·m (140 in. lb.)

Front Fan Assembly to Fan Shaft Nut Toque .............................................................15.8 N·m (140 in. lb.)

Fan/Pulley/Hub Assembly Fastener Torque ..............................................................6.8 N·m (60 in. lb.)

Flywheel Retaining Screw Torque ...............................................................................66.4 N·m (49 ft. lb.)

Lower Flywheel Cover Mounting Screw Torque ...................... into hex or weld nuts 9.9 N·m (88 in. lb.)

into Timmerman clips/nuts 2.2-2.8 N·m (20-25 in. lb.)

Lower Pulley Mounting Screw Torque ...................................................................... 24.3 N·m (215 in. lb.)

Governor

Governor Cross Shaft to Crankcase Running Clearance.......................................... 0.025/0.126 mm (0.0009/0.0049 in.)

Governor Cross Shaft O.D.

New .......................................................................................................................... 7.949/8.000 mm (0.3129/0.3149 in.)

Max. Wear Limit .....................................................................................................7.936 mm (0.3124 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 Gear Shaft-to-Governor Gear Running Clearance .................................. 0.090/0.160 mm (0.0035/0.0063 in.)

Governor Lever Nut Torque......................................................................................... 6.8 N·m (60 in. lb.)

1.11

Section 1 Safety and General Information

Ignition

Spark Plug Type (Champion

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 ........................................................................................ 0.203/0.305 mm (0.008/0.012 in.)

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

Rectifier-Regulator Fastener Torque ..................................................................... 4.0 N·m (35 in. lb.)

Muffler

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

Oil Filter

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

Piston, Piston Rings, and Piston Pin

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

Piston Pin Bore I.D.

New .................................................................................................................... 17.006/17.013 mm (0.6695/0.6698 in.)

Max. Wear Limit ............................................................................................... 17.025 mm (0.6703 in.)

or equivalent)....................................................... RC14YC

4.0 N·m (35 in. lb.) into used hole

Piston Pin O.D.

New .................................................................................................................... 16.995/17.000 mm (0.6691/0.6693 in.)

Max. Wear Limit ............................................................................................... 16.994 mm (0.6691 in.)

Top Compression Ring-to-Groove Side Clearance

LH630,LH640 .................................................................................................... 0.040/0.086 mm (0.0016/0.0034 in.)

LH685,LH690 .................................................................................................... 0.050/0.096 mm (0.0020/0.0038 in.)

LH750,LH755,LH760,LH775 ........................................................................... 0.014/0.041 mm (0.0005/0.0016 in.)

Middle Compression Ring-to-Groove Side Clearance

LH630,LH640 .................................................................................................... 0.040/0.086 mm (0.0016/0.0034 in.)

LH685,LH690 .................................................................................................... 0.030/0.076 mm (0.0012/0.0030 in.)

LH750,LH755,LH760,LH775 ........................................................................... 0.012/0.039 mm (0.0004/0.0015 in.)

Oil Control Ring-to-Groove Side Clearance

LH630,LH640 .................................................................................................... 0.046/0.196 mm (0.0018/0.0077 in.)

LH685,LH690 .................................................................................................... 0.046/0.196 mm (0.0018/0.0077 in.)

LH750,LH755,LH760,LH775 ........................................................................... 0.026/0.176 mm (0.0010/0.0070 in.)

Top and Middle Compression Ring End Gap

LH630,LH640

New Bore

Top Ring ......................................................................................................... 0.180/0.380 mm (0.0071/0.0150 in.)

Middle Ring ................................................................................................... 0.250/0.450 mm (0.0098/0.0177 in.)

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

²Measure 6 mm (0.236 in.) above the bottom of the piston skirt at right angles to the piston pin.

1.12

Piston, Piston Rings, and Piston Pin cont.

Top and Middle Compression Ring End Gap cont.

LH685,LH690

New Bore

Top Ring ..................................................................................... 0.180/0.430 mm (0.0071/0.0169 in.)

Middle Ring ............................................................................... 0.250/0.460 mm (0.0098/0.0181 in.)

Used Bore (Max.).............................................................................. 0.80 mm (0.0315 in.)

LH750,LH755,LH760 LH775

New Bore ........................................................................................... 0.250/0.56 mm (0.0098/0.022 in.)

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

Piston Thrust Face O.D.²

LH630,LH640

New ....................................................................................................76.968/76.986 mm (3.0302/3.0309 in.)

Max. Wear Limit ...............................................................................76.840 mm (3.0252 in.)

LH685,LH690

New ....................................................................................................79.963/79.981 mm (3.1481/3.1488 in.)

Max. Wear Limit ...............................................................................79.831 mm (3.1430 in.)

LH750,LH755,LH760 LH775

New ....................................................................................................82.973/82.991 mm (3.2666/3.2673 in.)

Max. Wear Limit ...............................................................................82.841 mm (3.3136 in.)

Section 1

Safety and General Information

Piston Thrust Face-to-Cylinder Bore² Running Clearance

LH630,LH640 ...........................................................................................0.014/0.057 mm (0.0005/0.0022 in.)

LH685,LH690 ...........................................................................................0.019/0.062 mm (0.0007/0.0024 in.)

LH750,LH755,LH760 LH775 ..................................................................0.015/0.058 mm (0.005/0.0022 in.)

Speed Control

Speed Control Bracket Assembly Fastener Torque .................................... 10.7 N·m (95 in. lb.) into new holes

7.3 N·m (65 in. lb.) into used holes

Stator

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

Valve Cover/Rocker Arms

Valve Cover Fastener Torque ........................................................................ 6.2 N·m (55 in. lb.)

Valves and Valve Lifters

Hydraulic Valve Lifter to Crankcase Running Clearance ......................... 0.0124/0.0501 mm (0.0005/0.0020 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 ...................................................................................... 7.134 mm (0.2809 in.)

Intake Valve Stem Diameter

New ........................................................................................................... 6.982/7.000 mm (0.2749/0.2756 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 6 mm (0.236 in.) above the bottom of the piston skirt at right angles to the piston pin.

1.13

Section 1 Safety and General Information

Valves and Valve Lifters cont.

Exhaust Valve Stem Diameter

New ......................................................................................................................... 6.970/6.988 mm (0.2744/0.2751 in.)

Valve Guide Reamer Size

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

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

Intake Valve Lift ............................................................................................................ 8.88 mm (0.3496 in.)

Exhaust Valve Lift ......................................................................................................... 8.88 mm (0.3496 in.)

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

Water Pump

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

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

General Torque Values

Metric Fastener T orque Recommendations for St andard Applications

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

Property Class

Noncritical

4.8

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

5.8

8.8

10.9

12.9

Fasteners

Into Aluminum

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

Property Class

Noncritical

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

Fasteners

Into Aluminum

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

1.14

Safety and General Information

English Fastener Torque Recommendations for Standard 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) ---------

1.15

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.

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2.1

Section 2 Tools & Aids

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2.2

Section 2

Tools & Aids

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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 that the tool teeth engage the flywheel ring gear teeth. The bosses will lock the tool and flywheel in position for loosening, tightening or removing with a puller.

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

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

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

Figure 2-1. Flywheel Holding Tool.

Rocker Arm/Crankshaft Tool

A spanner wrench to 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

Troubleshooting Guide

When troubles occur, be sure to check the simple causes which, at first, may seem too obvious to be considered. For example, a starting problem could be caused by an empty fuel tank.

Some common causes of engine troubles are listed below. Use these to locate the causing factors.

Engine Cranks But Will Not Start

1. Empty fuel tank.

2. Fuel shut-off valve closed.

3. Dirt or water in the fuel system.

4. Clogged fuel line.

5. Spark plug lead(s) disconnected.

6. Key switch or kill switch in “off” position.

7. Faulty spark plugs.

8. Faulty ignition module(s).

9. Carburetor solenoid malfunction.

10. Diode in wiring harness failed in open circuit mode.

11. Vacuum fuel pump malfunction, or oil in vacuum hose.

12. Vacuum hose to fuel pump leaking/cracked.

13. Battery connected backwards.

14. Safety interlock system engaged.

Engine Start s But Does Not Keep Running

1. Restricted fuel tank cap vent.

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

3. Faulty/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. Vacuum fuel pump malfunction, or oil in vacuum hose.

8. Leaking/cracked vacuum hose to fuel pump.

9. Intake system leak.

10. Diode in wiring harness failed in open circuit mode.

Section 3

Troubleshooting

Engines Start s 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 system problem.

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. Loose wires or connections that intermittently short the kill circuit of ignition system to ground.

4. Engine overheated-cooling system problem.

5. Faulty ignition module.

6. Faulty spark plugs.

7. Carburetor adjusted incorrectly.

8. Faulty interlock switch.

Engine Will Not Idle

1. Restricted fuel tank cap vent.

2. Dirt or water in the fuel system.

3. Faulty spark plugs.

4. Idle speed (RPM) adjusting screw improperly set.

5. Low compression.

6. Stale fuel and/or gum in carburetor.

7. Fuel supply inadequate.

8. Engine overheated-cooling system problem.

3.1

Section 3 Troubleshooting

Engine Overheats

1. Radiator, and/or cooling system components clogged, restricted, or leaking.

2. Excessive engine load.

3. Low crankcase oil level.

4. Low cooling system fluid level.

5. High crankcase oil level.

6. Lean fuel mixture.

7. Fan belt failed/off.

8. Cooling fan broken.

9. Water pump belt failed/broken.

10. Water pump malfunction.

11. Faulty carburetor.

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. (See "Engine Overheats")

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 or improperly assembled breather.

3. Breather reed broken.

4. Worn or broken piston rings.

5. Worn cylinder bore.

6. Worn valve stems or valve guides.

7. Crankcase overfilled.

8. Blow head gasket/overtightened.

Engine Loses or Uses Coolant

1. Overheating-See "Engine Overheats".

2. External leakage-from a joint connection, or a component of the cooling system.

3. Internal leakage-from a head gasket, or cooling system water jacket (passage) leak.

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 radiator, crankcase, cooling system components, and other external surfaces. Dirt or debris on these areas are causes of higher operating temperatures and overheating.

• Check for obvious fuel, oil, and coolant leaks, or damaged components. Excessive oil leakage can indicate a clogged or improperly assembled breather, worn or damaged seals and gaskets, or loose or improperly torqued fasteners. Coolant leaks can cause higher operating temperatures and overheating.

• Check the air cleaner assembly/components for damage or indications of leakage.

• Check the air cleaner element and inner element. Look for holes, tears, cracked/damaged sealing surfaces, or other damage that could allow unfiltered air into the engine. Also note if the elements are dirty or clogged. These could indicate that the engine has been underserviced.

• 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.

Oil Leaks from Oil Seals, Gaskets

1. Crankcase breather is clogged or inoperative.

2. Breather read broken.

3. Loose or improperly torqued fasteners.

4. Piston blowby or leaky valves.

5. Restricted exhaust.

3.2

• Check the coolant level within the reservoir and in the radiator. A low or improperly filled cooling system can cause overheating, excessive fuel consumption, and a lack of power.

Section 3

Troubleshooting

• Check the condition of the oil. Drain the oil into a container - the oil should flow freely. Check the appearance (color) of the oil, and for metal chips or foreign particles. A milky, opaque color denotes the presence of engine coolant in the crankcase oil.

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.

Basic Engine Tests

Crankcase Vacuum Test

A partial vacuum should be present in the crankcase when the engine is operating. Pressure in the crankcase (normally caused by a clogged or improperly 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.

Test the crankcase vacuum with the manometer as follows:

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 full throttle 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.

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.

No Crankcase Vacuum/Pressure in Crankcase

Possible Cause Solution

1. Crankcase breather clogged or inoperative.

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

3. Piston blowby or leaky valves. (Confirm by inspecting components.)

4. Restricted exhaust.

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.

1. Replace breather assembly (valve cover).

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.

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 engine 3-5 minutes to warm it up.

2. Remove spark plugs, dipstick, and air filter from engine.

3. Rotate crankshaft until piston (of cylinder being tested) is at top dead center (TDC) of compression stroke. You will need to hold the engine in this position while testing. The holding tool supplied with the tester can be used if the PTO end of the crankshaft is accessible. Slide the

holding tool onto the crankshaft and adjust the set screw to fit in the key slot. Install a 3/8" breaker bar into the square hole of the holding tool, so it is perpendicular to both the holding tool and crankshaft PTO. If the flywheel end is more accessible, you can use a breaker bar and socket on the flywheel nut/screw to hold it in position. You may need an assistant to hold the breaker bar during testing.

If the engine is mounted in a piece of equipment, you may be able to hold it by clamping or wedging a driven component. Just be certain that the engine cannot rotate off of TDC in either direction.

4. Install the adapter hose into the spark plug hole, but do not attach it to the tester at this time.

5. Connect an adequate air source to the tester.

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

7. Connect tester quick-disconnect to the adapter. Note the gauge reading and listen for escaping air at the carburetor intake, exhaust outlet, and oil fill/dipstick tube.

8. Check your test results against the table below:

Leakdown T est Results

Air escaping at oil fill tube .................................................................. Defective rings, worn cylinder walls, or blown

head gasket.

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

Air escaping from carburetor inlet ..................................................... 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.

Cooling Leakage T est

A pressure test can be performed as a simple means of determining whether the cooling system may have a problem. The test procedure, possible results, and recommended corrective action are covered in Section 7.

3.4

Air Cleaners

Section 4

Air Cleaner and Air Intake System

Section 4

Air Cleaner System

General

These engines are equipped with Kohler's heavy-duty, cyclonic air cleaner system. See Figure 4-1. The air cleaner includes a high-density, pleated paper main element (see Figure 4-2), and inner safety element (see Figure 4-3).

Figure 4-1. Heavy-duty Air Cleaner Assembly.

Figure 4-3. Air Cleaner Element with Inner Element.

Air Cleaner Element Service

Every 250 hours of operation (more often under extremely dusty or dirty conditions), replace the paper element and cylindrical inner element. Follow these steps:

1. Unhook the two retaining clips and remove the end cap from the air cleaner housing. See Figure 4-4.

Figure 4-2. Air Cleaner Element.

Figure 4-4. Removing End Cap.

2. Pull the air cleaner element out of the housing. See Figure 4-5.

4.1

Section 4 Air Cleaner and Air Intake System

Figure 4-5. Removing Air Cleaner Element.

3. Check the condition of the inner safety element. It should be replaced whenever it appears dirty, typically every other time the main element is replaced. Before removing it from the housing, clean the area around the base of the inner element, so dirt does not get into the engine. See Figure 4-6.

6. Reinstall the end cap, so the dust ejector valve faces down, and secure with the two retaining clips.

Air Cleaner Components

Air Cleaner Housing/End Cap Assembly

Make sure air cleaner housing including the dust ejector valve and the end cap is in good condition and not cracked. The two retainer clips should positively lock when the cap is installed.

Air Cleaner Hose

Inspect the air cleaner hose to make sure it is not cracked, split or damaged. Check that the air cleaner hose is securely clamped to both the air cleaner outlet and the inlet elbow on the carburetor.

Air Cleaner Mounting Base

Make sure the base is securely fastened to the upper valve cover screw locations and the screws securing the clamp bracket for the air cleaner housing are properly installed and tight.

Figure 4-6. Removing Cylindrical Inner Element.

4. The elements must be replaced when dirty. Do not attempt to clean the elements with

pressurized air, or other means, as the elements will be ruined. Handle new elements carefully; do not use if the sealing surfaces are bent or damaged. Replace any damaged or questionable components.

5. If it is being replaced, install the new inner element, Kohler Part No. 25 083 04-S, followed by the canister outer element; Kohler Part No. 25 083 01-S. Slide each fully into place in the housing.

Breather Hose

Make sure the hose is in good condition, not cracked, and properly secured to the breather cover and adapter fitting.

Figure 4-7. Air Cleaner Assembly .

4.2

Fuel System and Governor

Section 5

Fuel System and Governor

Section 5

Description

The Aegis horizontal twins use two different types of fuel systems; carbureted or electronic fuel injection (EFI).

This section covers the standard carbureted fuel systems. The EFI systems are covered in subsection 5B. The governor system, covered at the end of this section, is the same for both fuel systems.

WARNING: Explosive Fuel!

Fuel System Components

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

Fuel Recommendations

General Recommendations

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

• Do not add oil to the gasoline.

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

Fuel T y pe

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.

• Fuel Tank

• In-line Fuel Filter

• Fuel Pump

• Carburetor

• Fuel Lines

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

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 are not approved.

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.

5.1

Section 5 Fuel System and Governor

Fuel Filter

Most engines are equipped with an in-line fuel filter. Periodically inspect the filter and replace with a genuine Kohler filter every 200 operating hours.

Troubleshooting – Fuel System Related Causes

T est 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 vacuum and fuel lines to fuel

pump are secured and in good condition.

2. Check for fuel in the combustion chamber. a. Disconnect and ground the spark plug leads.

b. Close the choke on the carburetor.

c. Crank the engine several revolutions.

d. Remove a 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

fuel pump.

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

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

Fuel System T est s

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.

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 vent, fuel pickup screen, in-line filter, shutoff valve, and fuel line. Correct any observed problem and reconnect the line.

4. Check the operation of fuel pump. a. Remove the fuel line from the inlet fitting of

carburetor.

b. Crank the engine several times and observe

flow.

Fuel Pump

General

These engines are equipped with either a mechanical, or pulse style fuel pump. See Figure 5-1.

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.

Operation

Pulse Fuel Pump

Operation and pumping action is created by alternating positive and negative pressures within the crankcase. This pressure is transmitted to the pulse pump through a rubber hose connected between the pump and the crankcase. The pumping action causes the diaphragm on the inside of the pump to pull fuel in on its own downward stroke and to push it into the carburetor on its upward stroke. Two check valves prevent fuel from going backward through the pump.

5.2

Section 5

Fuel System and Governor

Mechanical Fuel Pump

The mechanical fuel pump is built into the #2 valve cover. The actuating arm of the pump extends down inside the cover and contacts one of the rocker arms. Downward movement of the rocker arm allows the pump diaphragm to flex down, drawing in fuel. As the rocker arm comes up, the fuel is forced out toward the carburetor.

Pulse Fuel Pump

3. Remove the vacuum line that connects the pump to the crankcase.

4. Install a new pump using the hex flange screws.

NOTE: Make sure the orientation of the new

pump is consistent with the removed pump. Internal damage may occur if installed incorrectly.

5. Connect vacuum line between the pump and crankcase.

6. Tighten the hex flange screws to 2.3 N·m (20 in. lb.).

7. Connect the fuel lines to the inlet and outlet fittings.

Mechanical Fuel Pump

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

2. Clean the area and remove the four screws securing the valve cover/pump assembly to the cylinder head. Loosen (but do not remove) the four valve cover screws on the opposite side.

Mechanical Fuel Pump

Figure 5-1. Fuel Pump Styles.

Replacing The Fuel Pump

Replacement pumps are available through your source of supply. To replace the pulse pump follow these steps. Note the orientation of pump before removing.

Pulse Fuel Pump

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

2. Remove the hex flange screws mounting fuel pump to support.

3. Lift the air cleaner mounting bracket up slightly and remove the valve cover/pump assembly. Remove and discard the old gasket.

4. Rotate the engine by hand while observing the actuating rocker arm. Stop rotating when end of the rocker arm is at the lowest point (spring is at maximum compression, and valve is open).

5. Position the new gasket onto the new cover/fuel pump assembly and install onto cylinder head. Align the air cleaner mounting bracket holes with the upper two valve cover screw holes.

6. Install the longer screws in the upper holes and the shorter screws in the lower holes. Finger tighten all eight valve cover mounting screws (four each side), then torque the screws to 6.2 N·m (55 in. lb.) in the sequence shown in Figure 5-2.

5.3

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Kohler LH640, LH775, LH755, LH690 User Manual

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