Kohler KT620 Service Manual

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KT610-KT620, KT715-KT745, KT720-KT726

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

Specifications

Tools and Aids

Troubleshooting

Air Cleaner/Intake

Fuel System

Governor System

Lubrication System

Electrical System

Starter System

Emission Compliant Systems

Disassembly/Inspection and Service

Reassembly

32 690 03 Rev. N

KohlerEngines.com

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Summary of Contents for Kohler KT620

Page 1 KT610-KT620, KT715-KT745, KT720-KT726 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...
Page 2 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 PRO oil and PRO filter. © REPAIRS/SERVICE PARTS Kohler genuine service parts can be purchased from Kohler authorized dealers. To find a local Kohler authorized dealer visit KohlerEngines.com or call 1-800-544-2444 (U.S. and Canada). 32 690 03 Rev. N KohlerEngines.com...
Page 4 KOHLER PRO Extended Life Oil Filter. Alternative full-synthetic oil). Remove spark plug(s) and pour engine oils and oil fi lters may be used with KOHLER about 1 oz. of engine oil into cylinder(s). Replace engines but require 100-Hour oil and oil fi lter change spark plug(s) and crank engine slowly to distribute intervals for proper maintenance.
Page 5 Specifications Engine Dimensions with Low Profile 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 7.2 mm (0.28) Center...
Page 6 Specifications Engine Dimensions with Low Profile 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 Profile Air Top of Low Profile Center of Gravity Surface Cleaner Removal Air Cleaner 134.0 mm (5.28 in.) 80.3 mm (3.16 in.)
Page 7 Specifications Engine Dimensions with Low Profile 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 Specifications Engine Dimensions with Low Profile 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 Exhaust Port #2...
Page 9 Specifications Engine Dimensions with Low Profile 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. N KohlerEngines.com...
Page 10 Specifications 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.) 141.5 mm (5.57 in.)
Page 11 Specifications 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.) Mounting Hole "A"...
Page 12 Specifications 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 Specifications 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 Specifications 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. N...
Page 15 Exceeding maximum angle of operation may cause engine damage from insufficient lubrication. Lubricate threads with engine oil prior to assembly. Any and all horsepower (hp) references by Kohler are Certified Power Ratings and per SAE J1940 & J1995 hp standards. Details on Certified Power Ratings can be found at KohlerEngines.com.
Page 16 Specifications KT600 KT610 KT715 KT730 KT720 KT724 TORQUE SPECIFICATIONS KT620 KT725 KT735 KT740 KT722 KT726 KT745 Blower Housing and Sheet Metal M3 HI-LO Screw 2.3 N·m (20 in. lb.) M4 HI-LO Screw 2.8 N·m (25 in. lb.) M5 Fasteners 6.2 N·m (55 in. lb.) into new hole 4.0 N·m (35 in.
Page 17 Specifications KT600 KT610 KT715 KT730 KT720 KT724 TORQUE SPECIFICATIONS KT620 KT725 KT735 KT740 KT722 KT726 KT745 Oil Pan Fastener 24.4 N·m (216 in. lb.) Oil Pump Screw (no torque sequence) 9.9 N·m (88 in. lb.) Oil Sentry ™ Pressure Switch 4.5 N·m (40 in.
Page 18 Specifications KT600 KT610 KT715 KT730 KT720 KT724 CLEARANCE SPECIFICATIONS KT620 KT725 KT735 KT740 KT722 KT726 KT745 Connecting Rod Connecting Rod-to-Crankpin Running Clearance 0.037/0.083 mm (0.0015/0.0033 in.) Max. Wear Limit 0.098 mm (0.0039 in.) Connecting Rod-to-Crankpin Side Clearance 0.261/0.67 mm (0.0102/0.0264 in.) Connecting Rod-to-Piston Pin Running Clearance 0.013/0.032 mm (0.0005/0.0013 in.)
Page 19 Specifications KT600 KT610 KT715 KT730 KT720 KT724 CLEARANCE SPECIFICATIONS KT620 KT725 KT735 KT740 KT722 KT726 KT745 Governor 7 mm Hex End Cross Shaft End Play 0.25/3.15 mm (0.010/0.124 in.) Governor Cross Shaft-to-Crankcase Running Clearance 0.025/0.126 mm (0.0009/0.0049 in.) Cross Shaft O.D.
Page 20 Specifications KT600 KT610 KT715 KT730 KT720 KT724 CLEARANCE SPECIFICATIONS KT620 KT725 KT735 KT740 KT722 KT726 KT745 Valves and Valve Tappets Clearance 0.101/0.152 mm (0.0040/0.0060 in.) Valve Tappet to Crankcase Running Clearance 0.013/0.073 mm (0.0005/0.0029 in.) Intake Valve Stem-to-Valve Guide Running 0.040/0.0780 mm (0.0016/0.0031 in.)
Page 21 Specifications 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 22 Shrader 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 K-Line Adapter Jumper Lead Wiring Harness Kohler 25 176 23-S...
Page 23 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. Reamer Handle Design Technology Inc. For hand reaming using Kohler 25 455 12-S reamer. DTI-K830 AIDS Description Source/Part No.
Page 24 Tools and Aids FLYWHEEL HOLDING TOOL ROCKER ARM/CRANKSHAFT TOOL A flywheel holding tool can be made out of an old junk A spanner wrench to lift rocker arms or turn crankshaft flywheel ring gear and used in place of a strap wrench. may be made out of an old junk connecting rod.
Page 25 Troubleshooting TROUBLESHOOTING GUIDE When troubles occur, be sure to check simple causes which, at first, may seem too obvious to be considered. For example, a starting problem could be caused by an empty fuel tank. Some general common causes of engine troubles are listed below and vary by engine specification. Use these to locate causing factors.
Page 26 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 27 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. Never run engine indoors or in enclosed spaces. Keep hands, feet, hair, and clothing away from all Engine exhaust gases contain poisonous carbon moving parts to prevent injury.
Page 28 Troubleshooting causes and conclusions. COMPRESSION TEST 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 battery is fully charged, 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 29 Troubleshooting Test Pressure Chart for Dual Gauge Tool Left Gauge Regulated Pressure Selection Right Gauge Reading in PSI 80 PSI Recommended for engines over 200 cc or those exhibiting high leakage at 35 PSI setting. 35 PSI Recommended for single 31.5 24.5 17.5...
Page 30 Air Cleaner/Intake AIR CLEANER NOTE: Operating engine with loose or damaged air cleaner components could cause premature These systems are CARB/EPA certified and components wear and failure. Replace all bent or damaged should not be altered or modified in any way. components.
Page 31 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 32 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 33 Fuel System CARBURETOR Walbro One-Barrel Carburetor Components WARNING Explosive Fuel can cause fires and severe burns. Do not fill fuel tank while engine is hot or running. 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.
Page 34 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, misfiring, loss Choke partially closed during Check choke lever/linkage to ensure of speed and power, governor operation.
Page 35 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 36 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 find a Kohler authorized dealer, visit KohlerEngines.com or call 1-800-544-2444 (U.S. and 22. Clean carburetor float bowl as required.
Page 37 Fuel System Smart-Choke ™ An air vane deflector assembly that operates by air from cooling fan opens choke partially when engine is running. When engine is cold, a spring on air vane deflector assembly, in conjunction with a bimetallic spring, holds choke closed for starting.
Page 38 Fuel System Smart-Choke Components ™ Precleaner Paper Element Air Cleaner Base Evap Hose Smart-Choke Adjustable Dual Position Solenoid Lead ™ Thermostat Thermostat Bracket Assembly Air Cleaner Gasket Control Assembly Breather Hose Stud Choke Unloaded Deflector Support Tab Intake Manifold Ignition Module Linkage (if Equipped) Air Vane Deflector...
Page 39 Fuel System 8. Original Design Smart-Choke System: Attach one Smart-Choke System Troubleshooting ™ wire of meter to red wire w/yellow tracer terminal of ™ assembly, and other wire to ground of bracket or to Original Design Smart-Choke System Oil ground strip of assembly body. ™...
Page 40 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 41 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 42 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 43 Calculations and unique software routines developed specifically 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 baffle.
Page 44 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 45 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 46 Fuel System Failure Modes Pause at RUN and attempt to CRANK engine. Limit cranking time to about 5 seconds. For first 4 failed crank attempts, choke Failure to Start will reposition at each attempt. After four (4) attempts, key OFF and make one final attempt to start.
Page 47 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 48 Fuel System 10. If movement is noted, attempt to crank and start Starting an Engine Equipped with eChoke engine. (Do not exceed 10 seconds of cranking.) ™ 1. This eChoke system automatically controls choke 11. If engine does not start: ™...
Page 49 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 50 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 51 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 flyweight mechanical governor.
Page 52 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-efficiency gerotor oil pump maintains high oil flow and oil pressure, even at low speeds and high operating temperatures.
Page 53 Lubrication System OIL SENTRY (if equipped) Installation ™ NOTE: Make sure oil level is checked before each use, 1. Apply pipe sealant with Teflon (Loctite 592™ ® ® ® and is maintained up to FULL or F mark on Thread Sealant or equivalent) to threads of switch. dipstick.
Page 54 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 55 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 56 Electrical System Ignition Systems These systems use a capacitive discharge (CD) coil. With CDI fixed timing, ignition timing and spark remains constant regardless of engine speed. Timing of spark is controlled by location of flywheel magnet group as referenced to engine TDC.
Page 57 Electrical System Wiring Diagram-Electronic Ignition System with Original Design Smart-Choke System ™ Solenoid Shift Inertia Driver Starter Solenoid Tang Green Starter Assembly Starter Assembly Oil Sentry White Violet (Charging) Spark Plug(s) (3-Terminal Switch) (AC Charging Leads) Rectifier-Regulator Flywheel Stator Rectifier-Regulator Ignition Module(s) Connector Assembly...
Page 58 Electrical System Wiring Diagram-Electronic Ignition System with Updated Design Smart-Choke System ™ Solenoid Shift Inertia Driver Starter Solenoid Tang Green Starter Assembly Starter Assembly Oil Sentry (Optional White Violet (Charging) Spark Plug(s) 1-Terminal Switch) (AC Charging Leads) Rectifier-Regulator Flywheel Stator Rectifier-Regulator Ignition Module(s) Connector...
Page 59 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 findings. 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 60 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 rectifier-regulator plug and/or wiring harness plug before doing any electric welding on equipment powered by engine.
Page 61 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 62 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 sufficient 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 63 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 64 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 commutator, and install positive (+) brush lead 1.
Page 65 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 66 To Carburetor Filter For engine to be Tier III compliant, it may be fitted 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 67 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 68 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 69 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 70 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 71 Disassembly/Inspection and Service Remove Air Cleaner and Carburetor Smart-Choke ™ Thermostat Bracket Assembly WARNING eChoke Bracket ™ Stepper Motor Explosive Fuel can cause fires and severe Assembly burns. NOTE: On engines equipped with eChoke stepper Do not fill fuel tank while engine is hot or ™, motor has a special retract routine that can be running.
Page 72 Disassembly/Inspection and Service 4. Remove screws securing rectifier-regulator to Remove Intake Manifold and Rectifier-Regulator backing plate and disconnect plug. 1. Remove screws securing intake manifold to cylinder 5. Use tip of a small screwdriver or similar small flat heads. Note which screws hold wiring clamp(s). tool to bend locking tang, then remove B+ (center 2.
Page 73 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 Remove Valve Covers and Cylinder Heads of engine.
Page 74 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 75 Disassembly/Inspection and Service Valve Seat Inserts Flywheel/Ignition/Breather Components Hardened steel alloy intake and exhaust valve seat inserts are press-fitted 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 76 Replace flywheel if it is cracked. Replace flywheel, crankshaft, and key if flywheel 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 flywheel if ring gear is damaged.
Page 77 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 78 Corresponding camshaft lobe(s) should also 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...
Page 79 Disassembly/Inspection and Service Inspection and Service Ring failure is usually indicated by excessive oil Check bearing area (big end) for excessive wear, score consumption and blue exhaust smoke. When rings fail, marks, running and side clearances (See Specifications). oil is allowed to enter combustion chamber where it is Replace rod and cap if scored or excessively worn.
Page 80 23°-33° Crosshatch journals. Subtract journal diameters from their respective bore diameters to get running clearances. Check results NOTE: Kohler pistons are custom-machined to exacting against values in Specifications. If running clearances tolerances. When over-sizing a cylinder, it are within specification, and there is no evidence of should be machined exactly 0.25 mm (0.010 in.)
Page 81 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 finish stones (220-280 grit) and polish bore to its final size.
Page 82 Reassembly NOTE: Make sure engine is assembled using all Install Flywheel End Oil Seal specified torque values, tightening sequences, 1. Make sure seal bore of crankcase is clean and free and clearances. Failure to observe specifications of any nicks or burrs. could cause severe engine wear or damage.
Page 83 Reassembly Crankshaft/Governor Gear/Oil Pump Components Locking Tab Thrust 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 84 Reassembly 4. Make sure FLY stamping on piston is facing toward Install Connecting Rods with Pistons and Rings flywheel 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 85 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 86 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 87 Reassembly NOTE: Before installing flywheel, make sure crankshaft taper and flywheel hub are clean, dry, and completely free of lubricants. Presence of lubricants can cause flywheel to be overstressed and damaged when screw is torqued to specifications. NOTE: Make sure flywheel key is installed properly in keyway. Flywheel can become cracked or damaged if key is not installed properly.
Page 88 Reassembly Assemble and Install Cylinder Heads Adjust Valve Clearance Valve Stem Seals Adjusters Retaining Push Rods Use a new seal whenever valve is removed, or if seal is deteriorated or damaged. Never reuse an old seal. Assemble Cylinder Heads Prior to installation, lubricate all components with engine oil, paying particular attention to lip of valve stem seal, valve stems, and valve guides.
Page 89 Reassembly Stamped Steel Valve Covers Install Valve Covers Stamped Steel Valve Cover RTV Sealant Plastic valve covers contain integral bolt hole spacers molded in place. Sealing of plastic valve covers is accomplished using a yellow colored O-ring. In stamped steel valve covers sealing is accomplished using RTV sealant.
Page 90 Reassembly 3. Position covers on cylinder heads. If a pulse style fuel pump is used valve cover with pulse fitting hole must be installed on side 2. Install screws in each cover and finger tighten. 4. Torque valve cover fasteners to 13.6 N·m (120 in. lb.), using sequence shown. Install Spark Plugs 1.
Page 91 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 Baffle Electric Starter Inner Baffle Ignition Module Intake Manifold Carburetor Gasket Air Cleaner Base Air Cleaner Element Rectifier-Regulator Dipstick Tube...
Page 92 Reassembly Install Ignition Modules Install Intake Manifold Torque Sequence Smart-Choke Deflector Support Tab ™ 1. On engines equipped with Smart-Choke , install air ™ vane deflector 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 93 Reassembly Install Carburetor Choke Unloader Linkage WARNING Explosive Fuel can cause fires and severe burns. Do not fill fuel tank while engine is hot or running. 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.
Page 94 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 Carburetor Nuts Choke Linkage Throttle Linkage NOTE: On engines equipped with eChoke stepper ™, motor has a special retract routine that can be...
Page 95 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 96 Reassembly Install Fuel Pump Install Oil Filter and Fill Crankcase with Oil NOTE: Make sure oil drain plug is installed and torqued WARNING to specification to prevent oil leakage. Explosive Fuel can cause fires and severe 1. Install oil drain plug. Torque plug to 13.6 N·m burns.
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