Kohler 6600 Series Service Manual
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Kohler 6600 Series Service Manual

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KT610-KT620, KT715-KT745
Service Manual
IMPORTANT:
Read all safety precautions and instructions carefully before operating equipment. Refer to operating
instruction of equipment that this engine powers.
Ensure engine is stopped and level before performing any maintenance or service.
2
Safety
3
Maintenance
5
Specifi cations
21
Tools and Aids
24
Troubleshooting
28
Air Cleaner/Intake
30
Fuel System
49
Governor System
50
Lubrication System
52
Electrical System
59
Starter System
63
Emission Compliant Systems
66
Disassembly/Inspection and Service
79
Reassembly
32 690 03 Rev. I
KohlerEngines.com
1

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Summary of Contents for Kohler 6600 Series

  • Page 1 KT610-KT620, KT715-KT745 Service Manual IMPORTANT: Read all safety precautions and instructions carefully before operating equipment. Refer to operating instruction of equipment that this engine powers. Ensure engine is stopped and level before performing any maintenance or service. Safety Maintenance Specifi cations Tools and Aids Troubleshooting Air Cleaner/Intake...

  • Page 2: Safety Precautions

    Safety SAFETY PRECAUTIONS WARNING: A hazard that could result in death, serious injury, or substantial property damage. CAUTION: A hazard that could result in minor personal injury or property damage. NOTE: is used to notify people of important installation, operation, or maintenance information. CAUTION WARNING WARNING...

  • Page 3: Maintenance Instructions

    ² Have a Kohler authorized dealer perform this service. REPAIRS/SERVICE PARTS Kohler genuine service parts can be purchased from Kohler authorized dealers. To fi nd a local Kohler authorized dealer visit KohlerEngines.com or call 1-800-544-2444 (U.S. and Canada). 32 690 03 Rev. I...

  • Page 4: Oil Recommendations

    OIL RECOMMENDATIONS STORAGE If engine will be out of service for 2 months or more We recommend use of Kohler oils for best performance. follow procedure below. Other high-quality detergent oils (including synthetic) of API (American Petroleum Institute) service class SJ 1.
  • Page 5 Specifi cations Engine Dimensions with Low Profi le or High Performance Air Cleaner-Flywheel Side 423.0 mm (16.65 in.) 136.7 mm (5.38 in.) 89.6 mm (3.53 in.) 50.1 mm (1.97 in.) Oil Fill and Dipstick Fuel Line Connection Mounting Hole "A" 136.9 mm (5.39 in.) (Yellow) Point...
  • Page 6 Specifi cations Engine Dimensions with Low Profi le or High Performance Air Cleaner-Oil Filter Side 355.1 mm (13.98 in.) 329.1 mm (12.96 in.) 159.4 mm (6.28 in.) Engine Mounting Low Profi le Air Top of Low Profi le Center of Gravity Surface Cleaner Removal Air Cleaner...
  • Page 7 Specifi cations Engine Dimensions with Low Profi le or High Performance Air Cleaner-Engine Mounting Surface (PTO End) 334.3 mm (13.16 in.) 72.8 mm (2.87 in.) 94.3 mm (3.71 in.) 48.1 mm (1.89 in.) 4 X 5/16-18 Evap Connection UNC-2B in. 50.0 mm (1.97 in.) 30°...
  • Page 8 Specifi cations Engine Dimensions with Low Profi le or High Performance Air Cleaner-Starter Side 55.8 mm (2.20 in.) 13.0 mm (0.51 in.) Mounting Hole "A" 40.8 mm (1.61 in.) Starter Stud 154.0 mm (6.06 in.) Engine Mounting 72.0 mm (2.83 in.) 92.0 mm (3.62 in.) Spark Plug Center Surface...
  • Page 9 Specifi cations Engine Dimensions with Low Profi le or High Performance Air Cleaner-Valve Cover Side Engine Mounting 87.6 mm (3.45 in.) 152.9 mm (6.02 in.) 4.4 mm (0.17 in.) Surface Mounting Hole "A" 39.8 mm (1.57 in.) 32 690 03 Rev. I KohlerEngines.com...
  • Page 10 Specifi cations Engine Dimensions with PRO Performance Air Cleaner-Flywheel Side 424.7 mm (16.72 in.) 136.7 mm (5.38 in.) 89.6 mm (3.53 in.) 50.1 mm (1.97 in.) Oil Fill and Dipstick Fuel Line Connection 136.9 mm (5.39 in.) Mounting Hole "A" (Yellow) Point 9.7 mm (0.38 in.)
  • Page 11 Specifi cations Engine Dimensions with PRO Performance Air Cleaner-Oil Filter Side 458.7 mm (18.06 in.) 265.2 mm (10.44 in.) 398.7 mm (15.70 in.) 166.5 mm (6.56 in.) Air Cleaner Evap Connection Top of Air Cleaner Center of Gravity Removal Point Engine Mounting 80.3 mm (3.16 in.) 51.2 mm (2.02 in.)
  • Page 12 Specifi cations Engine Dimensions with PRO Performance Air Cleaner-Engine Mounting Surface (PTO End) 4 X 5/16-18 UNC-2B 334.3 mm (13.16 in.) 72.8 mm (2.87 in.) 94.3 mm (3.71 in.) in. 16.5 mm (0.649 in.) Deep No Studs 50.0 mm (1.97 in.) 30°...
  • Page 13 Specifi cations Engine Dimensions with PRO Performance Air Cleaner-Starter Side 55.8 mm (2.20 in.) 13.0 mm (0.51 in.) Mounting Hole "A" 40.8 mm (1.61 in.) Starter Stud 154.0 mm (6.06 in.) Engine Mounting 72.0 mm (2.83 in.) 92.0 mm (3.62 in.) Spark Plug Center Surface Exhaust Port #2...
  • Page 14 Specifi cations Engine Dimensions with PRO Performance Air Cleaner-Valve Cover Side Engine Mounting 87.6 mm (3.45 in.) 152.9 mm (6.02 in.) 4.4 mm (0.17 in.) Surface Mounting Hole "A" 39.8 mm (1.57 in.) KohlerEngines.com 32 690 03 Rev. I...

  • Page 15: Engine Identification Numbers

    Lubricate threads with engine oil prior to assembly. Any and all horsepower (hp) references by Kohler are Certifi ed Power Ratings and per SAE J1940 & J1995 hp standards. Details on Certifi ed Power Ratings can be found at KohlerEngines.com.
  • Page 16 Specifi cations KT610 TORQUE SPECIFICATIONS KT620 KT715 KT725 KT730 KT735 KT740 KT745 Carburetor Mounting Nut 6.2-7.3 N·m (55-65 in. lb.) Connecting Rod Cap Fastener (torque in increments) Black Coating 11.3 N·m (100 in. lb.) 13.6 N·m (120 in. lb.) Gray Metallic Coating Crankcase Breather Assembly Outer Cover Stud...

  • Page 17: Clearance Specifications

    Specifi cations KT610 TORQUE SPECIFICATIONS KT620 KT715 KT725 KT730 KT735 KT740 KT745 Solenoid (Starter) Mounting Hardware 4.0-6.0 N·m (35-53 in. lb.) Nut, Positive (+) Brush Lead 8.0-11.0 N·m (71-97 in. lb.) Speed Control Bracket Fastener 10.7 N·m (95 in. lb.) into new holes 7.3 N·m (65 in.
  • Page 18 Specifi cations KT610 CLEARANCE SPECIFICATIONS KT620 KT715 KT725 KT730 KT735 KT740 KT745 Crankshaft End Play (free) 0.075/0.595 mm (0.0030/0.023 in.) Bore (in crankcase) 40.974/40.987 mm (1.6131/1.6137 in.) Max. Wear Limit 41.000 mm (1.6142 in.) Bore (in oil pan) 40.974/41.000 mm (1.6457/1.6142 in.) Crankshaft Bore (in oil pan)-to-Crankshaft Running Clearance 0.039/0.087 mm (0.0015/0.0034 in.)
  • Page 19 Specifi cations KT610 CLEARANCE SPECIFICATIONS KT620 KT715 KT725 KT730 KT735 KT740 KT745 Ignition Spark Plug Gap 0.76 mm (0.030 in.) Module Air Gap 0.203/0.305 mm (0.008/0.012 in.) Piston, Piston Rings, and Piston Pin Piston-to-Piston Pin Running Clearance 0.006/0.017 mm (0.0002/0.0007 in.) Pin Bore I.D.

  • Page 20: General Torque Values

    Specifi cations GENERAL TORQUE VALUES English Fastener Torque Recommendations for Standard Applications Bolts, Screws, Nuts and Fasteners Assembled Into Cast Iron or Steel Grade 2 or 5 Fasteners Into Aluminum Size Grade 2 Grade 5 Grade 8 Tightening Torque: N·m (in. lb.) ± 20% 8-32 2.3 (20) 2.8 (25)
  • Page 21 Schrader Valve Adapter Hose DTI-037 Wire Probe Set (2 pieces regular wire with clip; 1 piece fused wire) DTI-031 Hose Removal Tool, Dual Size/End (also sold as individual Kohler tool) DTI-033 SE Tools KLR-82408 Flywheel Puller For properly removing fl ywheel from engine.
  • Page 22 For reaming worn valve guides to accept replacement oversize valves. Can be used in low-speed drill press or with handle below for hand reaming. Design Technology Inc. Reamer Handle For hand reaming using Kohler 25 455 12-S reamer. DTI-K830 AIDS Description Source/Part No.
  • Page 23 Tools and Aids FLYWHEEL HOLDING TOOL ROCKER ARM/CRANKSHAFT TOOL A fl ywheel holding tool can be made out of an old junk A spanner wrench to lift rocker arms or turn crankshaft fl ywheel ring gear and used in place of a strap wrench. may be made out of an old junk connecting rod.

  • Page 24: Troubleshooting Guide

    Troubleshooting TROUBLESHOOTING GUIDE When troubles occur, be sure to check simple causes which, at fi rst, 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 and vary by engine specifi cation. Use these to locate causing factors.
  • Page 25 Troubleshooting EXTERNAL ENGINE INSPECTION Engine Loses Power NOTE: It is good practice to drain oil at a location away ● Dirty air cleaner element. from workbench. Be sure to allow ample time for ● Engine overheated. complete drainage. ● Excessive engine load. ●...

  • Page 26: Crankcase Vacuum Test

    Troubleshooting CRANKCASE VACUUM TEST WARNING WARNING Carbon Monoxide can cause severe nausea, Rotating Parts can cause severe injury. fainting or death. Stay away while engine is in operation. Avoid inhaling exhaust fumes. Engine exhaust gases contain poisonous carbon Keep hands, feet, hair, and clothing away from all monoxide.

  • Page 27: Compression Test

    Troubleshooting COMPRESSION TEST For Command Twins: A compression test is best performed on a warm engine. Clean any dirt or debris away from base of spark plug(s) before removing them. Be sure choke is off, and throttle is wide open during test. Compression should be at least 160 psi and should not vary more than 15% between cylinders.

  • Page 28: Air Cleaner

    Air Cleaner/Intake NOTE: Operating engine with loose or damaged air AIR CLEANER cleaner components could cause premature These systems are CARB/EPA certifi ed and components wear and failure. Replace all bent or damaged should not be altered or modifi ed in any way. components.

  • Page 29: Breather Tube

    Air Cleaner/Intake If air cleaner base requires removal, proceed as follows: Air Cleaner Base 1. Remove mounting screws for fuel pump (if equipped), and blower housing. 2. Raise or remove blower housing for access to air cleaner base. 3. Remove air cleaner components from base. 4.

  • Page 30: Fuel Pump

    3. Connect pulse line to new fuel pump and make sure Low permeation fuel line must be installed on carbureted opposite end is properly connected into valve cover. Kohler Co. engines to maintain EPA and CARB regulatory compliance. 4. Attach new fuel pump using screws. Torque screws to 2.8 N·m (25 in.
  • Page 31 Fuel System CARBURETOR Walbro One-Barrel Carburetor Components WARNING Explosive Fuel can cause fi res and severe burns. Do not fi ll fuel tank while engine is hot or running. Gasoline is extremely fl ammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well ventilated, unoccupied buildings, away from sparks or fl...
  • Page 32 Fuel System Troubleshooting-Carburetor Related Causes Condition Possible Cause Conclusion Engine runs rich (indicated by black, Clogged air cleaner. Clean or replace air cleaner. sooty exhaust smoke, misfi ring, loss Choke partially closed during Check choke lever/linkage to ensure of speed and power, governor operation.
  • Page 33 Fuel System Carburetor Adjustments Float Setting (Keihin Only) NOTE: Carburetor adjustments should be made only after engine has warmed up. Carburetor is designed to deliver correct fuel-to-air mixture to engine under all operating conditions. Main fuel jet is calibrated at factory and is not adjustable. Idle fuel adjusting needles are also set at factory and are not adjustable.
  • Page 34 Check spring loaded choke plate to make sure it kit is required. To obtain high altitude carburetor kit moves freely on shaft. information or to fi nd a Kohler authorized dealer, visit KohlerEngines.com or call 1-800-544-2444 (U.S. and 22. Clean carburetor fl oat bowl as required.
  • Page 35 Fuel System Smart-Choke ™ An air vane defl ector assembly that operates by air from cooling fan opens choke partially when engine is running. When engine is cold, a spring on air vane defl ector assembly, in conjunction with a bimetallic spring, holds choke closed for starting.
  • Page 36 Fuel System Troubleshooting Smart-Choke Related Causes ™ Condition Possible Cause Conclusion Engine starts hard, runs rough, or Choke not closing. Check choke lever/linkage to ensure stalls at idle speed. choke is operating properly. Check that bimetallic spring actuates freely. Engine runs rich (indicated by black, Choke partially closed during Check choke lever/linkage to ensure sooty exhaust smoke, misfi...
  • Page 37 Fuel System 11. With engine running, check voltage at bimetallic 13. If linkage is free and choke plate fails to open fully spring choke bracket assembly. Using a DVOM, after 2 minutes, check spring tension of bimetallic attach black lead of meter to ground screw on assembly.
  • Page 38 Fuel System Adjustable Thermostat High Position of Spring Tab Must be Models KT725, Models KT740, Adjustment Located in Lever Slot KT735 KT745 Range This Edge of Metallic Low Position of Ground Strap Must Adjustment Lever Slot Fall Within Range Adjustment Range Adjustable Thermostat Reset NOTE: Do not remove or loosen thermostat screws.
  • Page 39 Fuel System Dual Position Thermostat CDI Ignition Module MDI Ignition Module CDI Position MDI Position (Top View) (Top View) Spring Tab Must be Lever Slot Located in Lever Slot Dual Position Thermostat Installation NOTE: Thermostat temperature must be at room temperature before testing. 1.
  • Page 40 3. Activate starter switch. Release switch as soon as engine starts. If starter does not turn engine over, shut starter off immediately. Do not make further attempts to start engine until condition is corrected. Do not jump start using another battery. See your Kohler authorized dealer for trouble analysis.
  • Page 41 Calculations and unique software routines developed specifi cally for this Kohler engine operate a carburetor choke lever through an assembly (bracket, linkage) to control a stepper motor. Power and ground are supplied to master control and ignition module (Cylinder 2) which provides a signal for stepper motor by way of a control harness that is routed through cylinder #2 baffl...
  • Page 42 Fuel System eChoke System Standard Checks Blink Codes ™ NOTE: Procedures and troubleshooting may be easier NOTE: Use of any other type of lamp, other than LED, to perform with engine cover removed. Refer to could damage components. Disassembly/Inspection and Service and eChoke system is equipped with an MIL connector that Reassembly procedure.
  • Page 43 Fuel System Operational Tests Test Step Description of What is happening at Operation MIL Lamp Status Number Operation eChoke ™ Choke system will cycle Remove and reconnect Power Cycle to complete open and engine connector. then complete close. System activated, temperature read, waiting for engine to crank &...
  • Page 44 Fuel System Failure Modes Pause at RUN and attempt to CRANK engine. Limit cranking time to about 5 seconds. For fi rst 4 failed crank attempts, choke Failure to Start will reposition at each attempt. After four (4) attempts, key OFF and make one fi...
  • Page 45 Fuel System Troubleshooting eChoke Related Causes ™ Condition Possible Cause Conclusion Engine starts hard, runs rough, or Choke not closing/moving Stepper motor/bracket/link assembly stalls at idle speed. a. Incorrect set up of stepper must allow for full travel, make sure motor/link/bracket to link is located properly and carburetor.
  • Page 46 Fuel System 8. With engine/ambient temperature above 40°F (4°C), Starting an Engine Equipped with eChoke turn key switch from OFF to RUN. There should be a ™ NOTE: Do not crank engine continuously for more than noticeable movement of choke plate. 10 seconds at a time.
  • Page 47 Fuel System Governor/Throttle Control Connections Left Side Pull Cable Clamp Speed Control Lever Speed Setting Lever Choke Lever Right Side Pull Contact Point Choke Control Cable Dual Control High Speed High Speed Adjusting Throttle Control Cable Lever Stop Screw (Do Choke Linkage Screw Not Remove)
  • Page 48 If starter does not turn engine over, shut starter off immediately. Do not make further attempts to start engine until condition is corrected. Do not jump start using another battery. See your Kohler authorized dealer for trouble analysis. 4. For Operation – After engine starts, move throttle/...
  • Page 49 Governor System GOVERNOR Governed speed setting is determined by position of throttle control. It can be variable or constant, depending on engine application. Governor is designed to hold engine speed constant under changing load conditions. Most engines are equipped with a centrifugal fl...

  • Page 50: Check Oil Level

    Lubrication System This engine uses a combination pressure/splash lubrication system, delivering oil under pressure to crankshaft, connecting rod and main bearing surfaces. Other component areas are splash lubricated. A high-effi ciency gerotor oil pump maintains high oil fl ow and oil pressure, even at low speeds and high operating temperatures.
  • Page 51 Lubrication System OIL SENTRY (if equipped) Installation ™ NOTE: Make sure oil level is checked before each use, 1. Apply pipe sealant with Tefl on (Loctite 592™ ® ® ® and is maintained up to FULL or F mark on Thread Sealant or equivalent) to threads of switch.

  • Page 52: Spark Plugs

    Electrical System SPARK PLUGS Inspection Inspect each spark plug as it is removed from cylinder CAUTION head. Deposits on tip are an indication of general Electrical Shock can cause injury. condition of piston rings, valves, and carburetor. Do not touch wires while engine is running. Normal and fouled plugs are shown in following photos: Normal Spark Plug Component and Details...
  • Page 53 Electrical System Carbon Fouled Battery Maintenance Regular maintenance is necessary to prolong battery life. Battery Test To test battery, follow manufacturer's instructions. ELECTRONIC IGNITION SYSTEMS All ignition systems are designed to be trouble free for life of engine. Other than periodically checking/replacing spark plugs, no maintenance or timing adjustments are necessary or possible.
  • Page 54 Electrical System Ignition Systems These systems use a capacitive discharge (CD) coil. With CDI fi xed timing, ignition timing and spark remains constant regardless of engine speed. Timing of spark is controlled by location of fl ywheel magnet group as referenced to engine TDC.
  • Page 55 Electrical System Wiring Diagram-Electronic Ignition System with Smart-Choke System* ™ Solenoid Shift Inertia Driver Starter Solenoid Tang Green Starter Assembly Starter Assembly White Violet (Charging) Oil Sentry (Optional) Spark Plug(s) (AC Charging Leads) Rectifi er-Regulator Flywheel Stator Rectifi er-Regulator Ignition Module(s) Connector Assembly Intake Manifold Screw...
  • Page 56 Electrical System Electronic Ignition Systems Tests NOTE: Ignition tester must be used to test ignition on these engines. Use of any other tester can result in inaccurate fi ndings. Battery on unit must be fully charged and properly connected before performing tests (a battery that is hooked up or charged backward will crank engine but it won’t have spark).

  • Page 57: Battery Charging System

    Electrical System BATTERY CHARGING SYSTEM NOTE: Observe following guidelines to avoid damage to electrical system and components: ● Make sure battery polarity is correct. A negative (–) ground system is used. ● Disconnect rectifi er-regulator plug and/or wiring harness plug before doing any electric welding on equipment powered by engine.
  • Page 58 Electrical System 12/15/25 Amp Battery Charging Systems NOTE: Always zero ohmmeter on each scale before testing to ensure accurate readings. Voltage tests should be made with engine running at 3600 RPM with no load. Battery must be good and fully charged. When problems occur in keeping battery charged or battery charges at high rate, charging system or battery might be causing problems.
  • Page 59 Starter System NOTE: Do not crank engine continuously for more than 10 seconds. Allow a 60 second cool-down period between starting attempts. Failure to follow these guidelines can burn out starter motor. NOTE: If engine develops suffi cient speed to disengage starter but does not keep running (a false start), engine rotation must be allowed to come to a complete stop before attempting to restart engine.
  • Page 60 Starter System SOLENOID SHIFT STARTERS Starter Disassembly Solenoid Shift Starter Components NOTE: Do not reuse old retainer. NOTE: Do not soak armature or use solvent when cleaning. Wipe clean using a soft cloth, or use compressed air. 1. Remove hex nut and disconnect positive (+) brush lead/bracket from solenoid terminal.
  • Page 61 4 brushes and springs are serviced as a set. Use a new holes in metal clips must be up/out. Slide brush Kohler brush and spring kit if replacement is necessary. holder assembly down into place around 1. Perform steps 1-5 in Starter Disassembly.
  • Page 62 Starter System c. Install brush springs and snap on retainer caps. d. Hold starter assembly vertically on end housing, and carefully place tool (with extension) and assembled original brush holder assembly onto end of armature shaft. Slide brush holder assembly down into place around commutator, install positive (+) brush lead grommet in cutout of frame.
  • Page 63 To Carburetor Filter For engine to be Tier III compliant, it may be fi tted with a Kohler supplied canister vapor recovery system, or a system developed and installed by Original Equipment Manufacturer (OEM). Details on Kohler system are included below.
  • Page 64 Emission Compliant Systems SECONDARY EMISSION COMPLIANT SYSTEM Twin Secondary Air Induction System Hose To Exhaust Secondary Air Inlet Screen Hose To Carburetor Manifold Valve Assembly Hose To Exhaust Manifold Single Secondary Air Induction System Secondary Air Hose To Exhaust Hose To Carburetor Inlet Screen Valve Assembly Manifold...
  • Page 65 Emission Compliant Systems Remove Inlet Screen Inlet Components Secondary Air Valve Assembly Barb Inlet Screen 1. Remove inlet screen from secondary air valve assembly by grasping inlet screen at base and gently pulling away from valve assembly. 2. Use a soft brush to remove debris from screen. 3.
  • Page 66 Disassembly/Inspection and Service WARNING Before working on engine or equipment, disable engine as Accidental Starts can cause severe injury or follows: 1) Disconnect spark plug lead(s). 2) Disconnect death. negative (–) battery cable from battery. Disconnect and ground spark plug lead(s) before servicing.
  • Page 67 Disassembly/Inspection and Service Clean all parts thoroughly as engine is disassembled. Remove Throttle Controls Only clean parts can be accurately inspected and gauged for wear or damage. There are many Control Bracket Components commercially available cleaners that will quickly remove grease, oil and grime from engine parts.
  • Page 68 Disassembly/Inspection and Service Smart-Choke Remove Air Cleaner and Carburetor ™ Thermostat Bracket Assembly WARNING eChoke Bracket ™ Stepper Motor Explosive Fuel can cause fi res and severe Assembly burns. NOTE: On engines equipped with eChoke stepper Do not fi ll fuel tank while engine is hot or ™, motor has a special retract routine that can be running.
  • Page 69 Disassembly/Inspection and Service 4. Remove screws securing rectifi er-regulator to Remove Intake Manifold and Rectifi er-Regulator backing plate and disconnect plug. 1. Remove screws securing intake manifold to cylinder 5. Use tip of a small screwdriver or similar small fl at heads.
  • Page 70 Disassembly/Inspection and Service Remove Spark Plugs Remove Cylinder Heads Remove spark plug from each cylinder head. NOTE: Exhaust side is located on output shaft side of engine, while intake side is located on fan side of engine. Cylinder head number is embossed Remove Valve Covers and Cylinder Heads on outside of each cylinder head.
  • Page 71 Disassembly/Inspection and Service Inspection and Service Valve Details Exhaust Insert Exhaust Valve Intake Valve Intake Insert Dimension Intake Exhaust Seat Angle 89° 89° Insert O.D. 36.987/37.013 mm (1.4562/1.4572 in.) 32.987/33.013 mm (1.2987/1.2997 in.) Guide Depth 4 mm (0.1575 in.) 6.5 mm (0.2559 in.) Guide I.D.
  • Page 72 Disassembly/Inspection and Service Valve Seat Inserts Flywheel/Ignition/Breather Components Hardened steel alloy intake and exhaust valve seat inserts are press-fi tted into cylinder head. Inserts are not replaceable but can be reconditioned if not too badly pitted or distorted. If cracked or badly warped, cylinder head should be replaced.
  • Page 73 fl ywheel, crankshaft, and key if fl ywheel key is sheared or keyway is damaged. Inspect ring gear for cracks or damage. Kohler does not provide ring gears as a serviceable part. Replace fl ywheel if ring gear is damaged.
  • Page 74 Disassembly/Inspection and Service NOTE: Governor gear is held onto shaft by small Locking Tab Thrust Governor Gear molded tabs in gear. When gear is removed from Washer shaft, these tabs are destroyed and gear must Oil Pan Drain Plug be replaced. Therefore, remove gear only if absolutely necessary.
  • Page 75 Piston Ring Set Piston Pin Retainer be checked for wear or damage. Whenever tappets are Piston Piston Pin replaced, apply a liberal coating of Kohler lubricant to base of each new tappet before it is installed. Connecting Rod Connecting Rod End Cap...
  • Page 76 Disassembly/Inspection and Service Ring failure is usually indicated by excessive oil Inspection and Service Check bearing area (big end) for excessive wear, score consumption and blue exhaust smoke. When rings fail, marks, running and side clearances (See Specifi cations). oil is allowed to enter combustion chamber where it is Replace rod and cap if scored or excessively worn.
  • Page 77 (refer to Specifi cations). necessary. If bearing surfaces are worn or damaged, Oversize Kohler replacement piston will then fi t crankcase and/or oil pan will need to be replaced. correctly.
  • Page 78 Disassembly/Inspection and Service 3. When bore is within 0.064 mm (0.0025 in.) of Measuring Piston-to-Bore Clearance desired size, remove coarse stones and replace Piston Detail them with burnishing stones. Continue with burnishing stones until bore is within 0.013 mm (0.0005 in.) of desired size and then use fi nish stones (220-280 grit) and polish bore to its fi...
  • Page 79 Reassembly NOTE: Make sure engine is assembled using all Install Flywheel End Oil Seal specifi ed torque values, tightening sequences, 1. Make sure seal bore of crankcase is clean and free and clearances. Failure to observe specifi cations of any nicks or burrs. could cause severe engine wear or damage.
  • Page 80 Reassembly Locking Tab Thrust Crankshaft/Governor Gear/Oil Pump Components Governor Gear Washer Oil Pan Drain Plug Oil Seal Oil Pump Oil Sentry ™ Ball Spring Oil Pick-up Screen Ground Strap Outer Gerotor Gear Location Install Governor Cross Shaft 1. Lubricate governor cross shaft bearing surfaces in crankcase with engine oil.
  • Page 81 Reassembly 4. Make sure FLY stamping on piston is facing toward Install Connecting Rods with Pistons and Rings fl ywheel side of engine. Use a hammer with a rubber or wood grip and gently tap piston into cylinder. Be Piston and Connecting Rod Details careful oil ring rails do not spring free between bottom of ring compressor and top of cylinder.
  • Page 82 Reassembly RTV sealant is used as a gasket between oil pan Install Oil Seal in Oil Pan and crankcase. Refer to Tools and Aids for a listing of approved sealants. Always use fresh sealant. Using Oil Seal Component and Detail outdated sealant can result in leakage.
  • Page 83 Reassembly Flywheel/Ignition/Breather Components Install Breather Reed and Breather Reed Cover Breather Reed Cover Sealant Sealant Bead NOTE: RTV sealant should be allowed to cure a minimum of 1 hour before engine is started. 1. Install breather reed, followed by retainer over passage hole and mounting hole in crankcase.
  • Page 84 Reassembly NOTE: Before installing fl ywheel, make sure crankshaft taper and fl ywheel hub are clean, dry, and completely free of lubricants. Presence of lubricants can cause fl ywheel to be overstressed and damaged when screw is torqued to specifi cations. NOTE: Make sure fl...
  • Page 85 Reassembly Install Cylinder Heads Adjust Valve Clearance NOTE: Match numbers embossed on cylinder heads and crankcase. Adjusters Retaining Push Rods NOTE: When installing cylinder heads, new screws should always be used. New screws are supplied in gasket sets. NOTE: Push rods should always be installed in same position as before disassembly.
  • Page 86 Reassembly NOTE: Always use fresh sealant. Using outdated Install Valve Covers sealant can result in leakage. Refer to Tools and Aids for information on sealant dispenser. Valve Cover RTV Sealant NOTE: To ensure proper adhesion of sealant to both sealing surfaces, perform step 3 immediately (5 minutes maximum) after application of RTV.
  • Page 87 Reassembly External Engine Components Fixed Guard Air Cleaner Cover Debris Screen Blower Housing Hose Clamp Fuel Pump Hose Clip Fuel Line Fuel Filter Oil Filter Outer Baffl e Electric Starter Inner Baffl e Ignition Module Intake Manifold Carburetor Gasket Air Cleaner Base Air Cleaner Element Rectifi...
  • Page 88 Reassembly Install Ignition Modules Install Intake Manifold Torque Sequence Smart-Choke Defl ector Support Tab ™ 1. On engines equipped with Smart-Choke , install air ™ vane defl ector into intake manifold. Torque screw to 1 N·m (9 in. lb.). 2. Install intake manifold using new O-rings, with wiring harness attached, onto cylinder heads.
  • Page 89 Reassembly Install Carburetor Choke Unloader Linkage WARNING Explosive Fuel can cause fi res and severe burns. Do not fi ll fuel tank while engine is hot or running. Gasoline is extremely fl ammable and its vapors can explode if ignited. Store gasoline only in approved containers, in well ventilated, unoccupied buildings, away from sparks or fl...
  • Page 90 Reassembly Install Carburetor with eChoke Install External Governor Controls ™ Control Bracket Components eChoke Carburetor Components ™ Air Cleaner Base Solenoid Lead eChoke Bracket Stepper Motor ™ Assembly Choke Linkage Throttle Linkage Carburetor Governor Lever Governor Spring NOTE: On engines equipped with eChoke stepper ™, motor has a special retract routine that can be...
  • Page 91 Reassembly 1. Install governor lever onto governor cross shaft if Install Electric Starter Motor disconnected previously. 1. Install starter motor and lift bracket. 2. Make sure throttle linkage is connected to governor 2. Torque screws to 23.8 N·m (211 in. lb.). lever and throttle lever on carburetor.
  • Page 92 Reassembly Install Fuel Pump Install Oil Filter and Fill Crankcase with Oil NOTE: Make sure oil drain plug is installed and torqued to specifi cation to prevent oil leakage. WARNING Explosive Fuel can cause fi res and severe 1. Install oil drain plug. Torque plug to 13.6 N·m burns.
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