HD675, HD775 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 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. 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.
Maintenance MAINTENANCE INSTRUCTIONS WARNING Accidental Starts can cause severe injury or death. Disconnect and ground spark plug lead(s) before servicing. Before working on engine or equipment, disable engine as follows: 1) Disconnect spark plug lead(s). 2) Disconnect negative (–) battery cable from battery.
Maintenance OIL RECOMMENDATIONS We recommend use of Kohler oils for best performance. Other high-quality detergent oils (including synthetic) of API (American Petroleum Institute) service class SJ or higher are acceptable. Select viscosity based on air temperature at time of operation as shown in table below. STORAGE If engine will be out of service for 2 months or more follow procedure below. 1. Add Kohler PRO Series fuel treatment or equivalent to fuel tank.
Specifications ENGINE IDENTIFICATION NUMBERS Kohler engine identification numbers (model, specification and serial) should be referenced for efficient repair, ordering correct parts, and engine replacement. Model . . . . . . . . . . . . . . . . . . . . . HD675 HD Series Engine Vertical Shaft Numerical Designation Specification . . . . . . . . . . . . . . . HD675-3000 Serial . . . . . . . . . . . . . . . . . . . . .
Specifications TORQUE SEQUENCES HD675 Oil Pan Fasteners HD675 HD775 1 6 3 4 5 2 7 HD775 Oil Pan Fasteners 1 3 6 5 4 2 Valve Cover Fasteners 3 2 1 4 TORQUE SPECIFICATIONS2,5 HD675 HD775 Air Cleaner Base Stud Fastener Crankcase Fastener 8 N·m (71 in. lb.) 8 N·m (71 in. lb.) Blower Housing Stud Nut 10 N·m (89 in. lb.) 8 N·m (71 in. lb.) 2 5 Values are in Metric units. Values in parentheses are English equivalents. Lubricate threads with engine oil prior to assembly. 6 KohlerEngines.
Specifications TORQUE SPECIFICATIONS2,5 HD675 HD775 Brake (if equipped) Mounting Fastener 9.5 N·m (84 in. lb.) Breather Cover Fastener 10 N·m (89 in. lb.) Carburetor Stud Fastener Stud Auto Choke Arm Assembly Nut (if equipped) Auto Choke Arm Assembly Screw (if equipped) 8 N·m (71 in. lb.) 5 N·m (44 in. lb.) 8.5 N·m (75 in. lb.) 2.3 N·m (20 in. lb.) Connecting Rod Cap Fastener (torque in increments) 12.5 N·m (110 in. lb.
Specifications TORQUE SPECIFICATIONS2,5 HD675 Muffler Exhaust Stud Lock Nut Shoulder Screw HD775 5.0 N·m (44 in. lb.) 9.5 N·m (84 in. lb.) 9.5 N·m (84 in. lb.) Oil Pan (torque sequence on page 6 ) Oil Drain Plug6 Fastener 13.6 N·m (120 in. lb.) 11.0 N·m (98 in. lb.) 14.7 N·m (130 in. lb.) Retractable Starter Fastener 8 N·m (71 in. lb.) Rocker Arm Stud Pivot Jam Nut 13.6 N·m (120 in. lb.) 9.5 N·m (84 in. lb.) Speed Control Bracket Assembly Fastener 8 N·m (71 in. lb.
Specifications CLEARANCE SPECIFICATIONS2 HD675 Crankshaft End Play (free) Bore in Oil Pan I.D. Bore in Oil Pan Running Clearance Bearing (flywheel) Journal O.D. 0.427/1.298 mm (0.0168/0.05110 in.) 27.050/27.071 mm (1.06496/1.06578 in.) 0.008/0.121 mm (0.0031/0.00476 in.) 25.005/25.019 mm 24.975/24.989 mm (0.9844/0.9850 in.) (0.9832/0.9838 in.) 0.025 mm (0.0009 in.) 0.025 mm (0.0009 in.) 0.025 mm (0.0009 in.) 0.025 mm (0.0009 in.) 26.95/26.97 mm (1.061/1.062 in.) 0.025 mm (0.0009 in.) 0.025 mm (0.0009 in.
Specifications CLEARANCE SPECIFICATIONS2 Piston, Piston Rings, and Piston Pin Pin Bore I.D. Pin O.D. Top and Center Compression Ring Side Clearance New Bore Top and Center Compression Ring End Gap New Bore Top Center Thrust Face O.D. Piston Thrust Face-to-Cylinder Bore Running Clearance HD675 HD775 13.002/13.008 mm (0.5118/0.5121 in.) 12.990/12.996 mm (0.5114/0.5116 in.) 18.000/18.008 mm (0.7086/0.7089 in.) 17.990/17.996 mm (0.7082/0.7085 in.) 0.001/0.020 mm (0.00004/0.00080 in.) 0.1/0.25 mm (0.0039/0.
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 Tightening Torque: N·m (in. lb.) ± 20% 8-32 2.3 (20) 10-24 3.6 (32) 10-32 3.6 (32) 1/4-20 7.9 (70) 1/4-28 9.6 (85) 5/16-18 17.0 (150) 5/16-24 18.7 (165) 3/8-16 29.4 (260) 3/8-24 33.9 (300) Grade 5 Grade 8 2.8 (25) 4.5 (40) 4.5 (40) 13.0 (115) 15.8 (140) 28.3 (250) 30.
Tools and Aids Certain quality tools are designed to help you perform specific disassembly, repair, and reassembly procedures. By using these tools, 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 a list of tools and their source. NOTE: Not all tools listed are required to service this engine. SEPARATE TOOL SUPPLIERS Kohler Tools Contact your local Kohler source of supply.
Tools and Aids TOOLS Description Flywheel Puller For properly removing flywheel from engine. Flywheel Anchor Bolts, Washers, Nuts Tool Used with Flywheel Puller for properly removing flywheel from 5400 Series engine. Hose Removal Tool, Dual Size/End (also available in EFI Service Kit) Used to properly remove fuel hose from engine components. Ignition System Tester For testing output on all systems, including CD. Inductive Tachometer (Digital) For checking operating speed (RPM) of an engine.
Tools and Aids FLYWHEEL HOLDING TOOL ROCKER ARM/CRANKSHAFT TOOL A flywheel holding tool can be made out of an old junk flywheel ring gear and used in place of a strap wrench. 1. Using an abrasive cut-off wheel, cut out a six tooth segment of ring gear as shown. 2. Grind off any burrs or sharp edges. 3. Invert segment and place it between ignition bosses on crankcase so tool teeth engage flywheel ring gear teeth.
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. Engine Cranks But Will Not Start ● Battery connected backwards. ● Blown fuse. ● Choke not closing. ● Clogged fuel line or fuel filter. ● Empty fuel tank.
Troubleshooting Engine Uses Excessive Amount of Oil ● Loose or improperly torqued fasteners. ● Blown head gasket/overheated. ● Breather reed broken. ● Clogged, broken, or inoperative crankcase breather. ● Crankcase overfilled. ● Incorrect oil viscosity/type. ● Worn cylinder bore. ● Worn or broken piston rings. ● Worn valve stems/valve guides. Oil Leaks from Oil Seals, Gaskets ● Breather reed broken. ● Clogged, broken, or inoperative crankcase breather. ● Loose or improperly torqued fasteners.
Troubleshooting CRANKCASE VACUUM TEST WARNING Carbon Monoxide can cause severe nausea, fainting or death. Avoid inhaling exhaust fumes. Never run engine indoors or in enclosed spaces. Engine exhaust gases contain poisonous carbon monoxide. Carbon monoxide is odorless, colorless, and can cause death if inhaled. WARNING Rotating Parts can cause severe injury. Stay away while engine is in operation. Keep hands, feet, hair, and clothing away from all moving parts to prevent injury.
Troubleshooting COMPRESSION TEST These engines are equipped with an automatic compression release (ACR) mechanism. It is difficult to obtain an accurate compression reading because of ACR mechanism. As an alternative, use cylinder leakdown test described below. CYLINDER LEAKDOWN TEST A cylinder leakdown test can be a valuable alternative to a compression test. By pressurizing combustion chamber from an external air source you can determine if valves or rings are leaking, and how badly.
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. 80 72 64 56 48 40 32 24 16 8 0 35 PSI Recommended for single cylinder walk-behind push mower applications. 35 31.5 28 24.5 21 17.5 14 10.5 7 3.
Air Cleaner/Intake AIR CLEANER These systems are CARB/EPA certified and components should not be altered or modified in any way. Air Cleaner Components BREATHER TUBE Make sure both ends of breather tube are properly connected. AIR COOLING D WARNING C B Hot Parts can cause severe burns. Do not touch engine while operating or just after stopping. A Never operate engine with heat shields or guards removed.
Fuel System Typical carbureted fuel system and related components include: ● Fuel tank. ● Fuel lines. ● In-line fuel filter (if equipped). ● In-nipple fuel filter (if equipped). ● Fuel shut-off valve (if equipped). ● Carburetor. ● Fuel pump (if equipped) and second in-nipple fuel filter after tee fitting. Fuel tank outlet is located above carburetor inlet, allowing gravity to feed fuel through in-line filter and fuel line to carburetor. Engines equipped with a pulse fuel pump allows for complete fuel usage.
Fuel System FUEL SYSTEM TESTS When engine starts hard, or turns over but will not start, fuel system might be causing problems. Test fuel system by performing following tests. 1. Check for fuel in combustion chamber. a. Disconnect and ground spark plug lead. b. Close choke on carburetor. c. Crank engine several times. d. Remove spark plug and check for fuel at tip. 2. Check for fuel flow from tank to carburetor. a. Remove fuel line from inlet fitting of carburetor. b.
Fuel System CARBURETOR WARNING Explosive Fuel can cause fires and severe burns. Do not fill fuel tank while engine is hot or running. Typical One-Barrel Carburetor Components M A F G H I K J N Bowl Retaining Screw Gasket Troubleshooting Checklist When engine starts hard, runs rough, or stalls at low idle speed, check these areas before adjusting or disassembling carburetor. 1. Make sure fuel tank is filled with clean, fresh gasoline. 2.
Fuel System Troubleshooting-Carburetor Related Causes Condition Engine starts hard, runs rough, or stalls at idle speed. Engine runs rich (indicated by black, sooty exhaust smoke, misfiring, loss of speed and power, governor hunting, or excessive throttle opening). Possible Cause Low idle fuel mixture (some models)/ speed improperly adjusted. Clogged air cleaner. Choke partially closed during operation. Dirt under fuel inlet needle. Conclusion Adjust idle speed screw or clean carburetor.
Fuel System Carburetor Servicing High Altitude Operation WARNING Accidental Starts can cause severe injury or death. Disconnect and ground spark plug lead(s) before servicing. Before working on engine or equipment, disable engine as follows: 1) Disconnect spark plug lead(s). 2) Disconnect negative (–) battery cable from battery. NOTE: Main and slow jets are fixed and size specific and can be removed if required. Fixed jets for high altitudes are available.
Fuel System Cover, Element, and Breather Cover C D B A A C 1. 2. 3. 4. Air Cleaner Cover B Element Breather Cover D Air Cleaner Base Remove air cleaner cover, air cleaner, and breather cover from air cleaner base. Check choke linkage for binding or debris build up. Gently actuate linkage and observe that choke plate has full range of movement (open and close). Remove vacuum hose from carburetor vacuum fitting. Attach a vacuum gauge or manometer to carburetor vacuum fitting.
Fuel System Auto Choke Components - Link Design B A E D C B When engine is cold, spring around base of choke shaft holds choke closed for starting. When engine starts, governor closes throttle from wide open to set governor speed. As throttle closes, link between throttle and choke operates choke to a slightly open position. After engine warms up, bimetallic spring overcomes choke shaft spring force and holds choke completely open. Use these steps to check function of link design auto choke. 1.
Governor System GOVERNOR Governor Components C D B A E J F K I H P G T Q L S M R N O A J K F I G H B Brake Spring (if equipped) C Brake Lever (if equipped) D Fixed Speed Control Bracket Adjustment F E High Speed Tab Governor Lever G Nut H Screw I Linkage Spring K Linkage L Variable Speed Control Lever A 28 Governor Cross Shaft Governor Spring J KohlerEngines.com 14 690 10 Rev.
Governor System M Intermediate Control Lever N Control Spring O High Speed Adjusting Screw P Regulating Pin Q Flyweight(s) R Governor Gear S Governor Gear Shaft T Governor Shaft Retainer 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.
Lubrication System These engines use a splash lubrication system, supplying necessary lubrication to crankshaft, camshaft, connecting rod, and valve train components. Lubrication Components C A B E D A 1/4 Turn Cap E Oil Fill Cap/ Dipstick D B Threaded Cap OIL RECOMMENDATIONS Refer to Maintenance. CHECK OIL LEVEL NOTE: To prevent extensive engine wear or damage, never run engine with oil level below or above operating range indicator on dipstick. Ensure engine is cool and level.
Lubrication System Crankcase plug 1. Disable engine by disconnecting spark plug. 2. Clean area around oil fill cap/dipstick. Remove oil fill cap/dipstick. 3. Remove crankcase plug on bottom of engine; drain oil into appropriate container. 4. Apply thread sealant around three full threads of drain plug; reinstall drain plug. Torque drain plug to 13.6 N·m (120 in. lb.). 5. Fill crankcase with new oil. Level should be at top of indicator on dipstick. 6. Reinstall oil fill cap/dipstick and tighten securely. 7.
Electrical System SPARK PLUGS CAUTION Electrical Shock can cause injury. Do not touch wires while engine is running. Spark Plug Component and Details Inspection Inspect each spark plug as it is removed from cylinder head. Deposits on tip are an indication of general condition of piston rings, valves, and carburetor. Normal and fouled plugs are shown in following photos: Normal A B Plug taken from an engine operating under normal conditions will have light tan or gray colored deposits.
Electrical System ELECTRONIC IGNITION SYSTEM Inductive Discharge Ignition System Carbon Fouled H J G I E D Soft, sooty, black deposits indicate incomplete combustion caused by a restricted air cleaner, over rich carburetion, weak ignition, or poor compression. Overheated Chalky, white deposits indicate very high combustion temperatures. This condition is usually accompanied by excessive gap erosion.
Electrical System Electronic Ignition System Tests (Retractable Start) Test Ignition System Remove spark plug. Check condition of spark plug. Make sure gap is set to 0.76 mm (0.030 in.). Install spark plug and torque to 27 N·m (20 ft. lb.). Condition Spark plug is not receiving ignition pulse. Spark plug in bad condition. Possible Cause Spark Plug Spark Plug Conclusion Check gap and adjust if necessary; reinstall plug. Replace plug, set gap, and install.
Electrical System Electronic Ignition System Tests (Electric Start) 3. Set an ohmmeter to Rx1K or Rx10K scale and zero. Connect one ohmmeter lead to module kill lead tab and connect other lead into spark plug cap. Resistance should be 5-15 K ohms. If resistance is not in this range, replace ignition module. 4. Test ignition/key switch following equipment manufacturer's instructions. Refer to equipment manufacturer's manual.
Electrical System Rectified Only (non-regulated) Systems (if equipped) Some engines are equipped with a rectified (in-line diode) only, non-regulated 1 amp charging system. Diode (rectifier) is a sealed in-line wiring jumper between stator and a battery (B+) connection (OEM location). Jumper features male/female bullet connectors and can only be installed one way. Diode (rectifier) converts AC voltage coming from stator to DC voltage only.
Electrical System 1 Amp Battery Charging System NOTE: Zero ohmmeters on each scale to ensure accurate readings. Voltage tests should be made with engine running at high speed - no load. Battery must be fully charged. If low, recharge or replace battery as necessary. To test charging system for no charge to battery: 1. Connect DC voltmeter red positive (+) lead to positive (+) terminal of battery. Connect voltmeter black negative (-) lead to negative (-) terminal of battery. Observe battery voltage.
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.
Starter System 2. Use a known, good, fully-charged battery and jumper cables to test starter motor. Be sure drive unit is in neutral, blade is off (if equipped with a blade brake clutch (BBC) assembly), and/or handlebar bail lever is in run position. Disconnect starter wire from application. Connect one end of positive (+) jumper cable to bullet terminal of red starter wire and connect other end to positive (+) terminal of battery. Connect one end of negative (-) jumper cable to negative terminal of battery.
Starter System RETRACTABLE STARTERS WARNING Uncoiling Spring can cause severe injury. Wear safety goggles or face protection when servicing retractable starter. Retractable starters contain a powerful, recoil spring that is under tension. Always wear safety goggles when servicing retractable starters and carefully follow instructions in Retractable Starter for relieving spring tension.
Starter System Pawls (dogs) Replacement 1. Install a clamp to hold pulley in starter housing and prevent it from rotating. 2. Unscrew center screw and lift off drive plate. 3. Note positions of pawls and pawl springs before removing. Remove parts from pulley. 4. Install pawl springs and pawls into pawl slots of pulley. All parts must by dry. 5. Position drive plate over pawls, aligning actuating slots in place with raised sections on each drive pawl. Torque center screw to 5-6 N·m (44-54 in. lb.). 6.
Disassembly/Inspection and Service WARNING Accidental Starts can cause severe injury or death. Disconnect and ground spark plug lead(s) before servicing. Before working on engine or equipment, disable engine as follows: 1) Disconnect spark plug lead(s). 2) Disconnect negative (–) battery cable from battery.
Disassembly/Inspection and Service Clean all parts thoroughly as 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 manufacturer's instructions and safety precautions carefully. Make sure all traces of cleaner are removed before engine is reassembled and placed into operation.
Disassembly/Inspection and Service 1. Loosen knob and remove air cleaner cover. 2. Remove precleaner and paper element. 3. Remove nuts securing air cleaner base to carburetor studs and screw securing base to crankcase. 4. Using Hose Removal Tool (See Tools and Aids), carefully remove breather hose from air cleaner base. (Other end is attached to crankcase.) 5. If engine is equipped with fuel pump, carefully disconnect clamp securing vent hose to air cleaner base. 6.
Disassembly/Inspection and Service 3. Remove nuts securing fuel pump bracket to engine. Remove fuel pump bracket, fuel pump, fuel lines from engine. On engines equipped with a fuel pump, top nut that secure fuel pump bracket also secures speed control assembly bracket to stud in crankcase.
Disassembly/Inspection and Service 4. Disconnect governor linkage and linkage spring from carburetor. 5. Remove carburetor. 6. Remove nuts securing arm assembly to muffler. Second nut is located behind arm assembly base securing it to top of muffler. 7. Remove arm assembly from muffler. Remove Governor Lever Loosen governor lever nut and slide lever off governor shaft.
Disassembly/Inspection and Service Remove Ignition Module 1. Disconnect kill lead from ignition module. 2. Remove screw and stud securing ignition module. Mark stud for identification during reassembly. Disconnect Flywheel Brake Spring (if equipped) Grasp 1 end of flywheel brake spring with a pliers and stretch it to disconnect it. Remove Flywheel 1. Using a flywheel strap wrench to hold flywheel, remove nut inside drive cup. 2.
Disassembly/Inspection and Service Cylinder Head Components O L K N J M H E I B F G D C A A Valve Cover B Jam Nut C Rocker Arm Pivot D Rocker Arms E Rocker Arm Stud F Push Rod G Push Rod Guide Plate H Valve Keeper I Valve Spring J Intake Valve Seal K Spark Plug L Baffle M Cylinder Head N Valve O Dowel Pin Remove Valve Cover NOTE: Valve cover is sealed to cylinder head using RTV silicone sealant.
Disassembly/Inspection and Service Remove Guide Plate 1. Remove guide plate from rocker studs. 2. Note orientation of guide plate (tabs down) for use during reassembly. Remove Cylinder Head 1. Remove screws securing cylinder head. 2. Remove cylinder head, noting positioning of dowels. 3. Remove head gasket and discard. Remove Valve Assembly NOTE: Only intake valve has a seal. There is no valve seal on exhaust side. 1. Push down on valve spring keepers to release valve springs from valve stems. 2.
Disassembly/Inspection and Service After cleaning, check flatness of cylinder head and corresponding top surface of crankcase, using a surface plate or precision straight edge and feeler gauge. Maximum allowable out of flatness is 0.08 mm (0.003 in.). Carefully inspect valve mechanism parts. Inspect valve springs and related hardware for excessive wear or distortion. Check valves and valve seats for evidence of deep pitting, cracks, or distortion. Check running clearance between valve stems and guides.
Disassembly/Inspection and Service Crankcase Components A B E C D F G K J I H P N L S M O Q R A Crankcase Oil Seal B Crankcase C Governor Cross Shaft D Camshaft E Piston Pin Retainer F Piston Pin G Piston H Piston Ring Set I Connecting Rod J Connecting Rod End Cap K Crankshaft L Retainer M Governor Shaft N Governor Gear O Governor Washer P Governor Cup Q Oil Pan R Oil Pan Oil Seal S Dipstick Assembly (if equipped) Remove Oil Pan 1.
Disassembly/Inspection and Service ACR These engines are equipped with an ACR mechanism. ACR lowers compression at cranking speeds to make starting easier. ACR mechanism consists of a decompression weight and arm mounted to camshaft, and activated by a return spring. When engine is rotating at low cranking speeds (1000 RPM or less), decompression weight holds arm so it protrudes above heel of exhaust lobe. This holds exhaust valve off its seat during first part of compression stroke.
Disassembly/Inspection and Service Some important points to remember when servicing piston rings: 1. Cylinder bore must be de-glazed before service ring sets are used. 2. If cylinder bore does not need re-boring and if old piston is within wear limits and free of score or scuff marks, old piston may be reused. 3. Remove old rings and clean up grooves. Never reuse old rings. 4. Before installing new rings on piston, place top 2 rings, each in turn, in its running area in cylinder bore and check end gap.
Disassembly/Inspection and Service Remove Crankshaft Remove crankshaft. Inspection and Service Inspect gear teeth of crankshaft and ACR gear. If any teeth are badly worn or chipped, or if some are missing, replacement of crankshaft will be necessary. Inspect crankshaft bearing surfaces for scoring, grooving, etc. Measure running clearance between crankshaft journals and their respective bearing bores.
Reassembly Crankcase Components A B E C D F G K J I H P N L S M O Q R A Crankcase Oil Seal B Crankcase C Governor Cross Shaft D Camshaft E Piston Pin Retainer F Piston Pin G Piston H Piston Ring Set I Connecting Rod J Connecting Rod End Cap K Crankshaft L Retainer M Governor Shaft N Governor Gear O Governor Washer P Governor Cup Q NOTE: NOTE: NOTE: NOTE: Dipstick Assembly (if equipped) Make sure engine is assembled using all specified torque values, tightening se
Reassembly Install Piston and Connecting Rod NOTE: Proper orientation of piston and connecting rod inside engine is extremely important. Improper orientation can cause extensive wear or damage. 1. Stagger piston rings in grooves until end gaps are 60° or more apart. Lubricate cylinder bore, crankshaft journal, connecting rod journal, piston, and rings with engine oil. 2. Compress piston rings using a piston ring compressor. 3. Position triangle on top of piston toward push rod chamber. 4.
Reassembly Sealant Pattern HD775 A 4. Guide oil pan onto crankcase, ensuring camshaft and governor gear align with their mating surfaces. Rotate crankshaft slightly to help engage governor gear. 5. Install and finger tighten screws, securing oil pan to crankcase. 6. Use torque sequence shown and torque oil pan screws to: Model Torque HD675 11.0 N·m (98 in. lb.) HD775 14.7 N·m (130 in. lb.) HD675 A A 1.5 mm (1/16 in.) bead of sealant.
Reassembly Cylinder Head Components O L K N J M H E I B F G D C A A Valve Cover B Jam Nut C Rocker Arm Pivot D Rocker Arms E Rocker Arm Stud F Push Rod G Push Rod Guide Plate H Valve Keeper I Valve Spring J Intake Valve Seal K Spark Plug L Baffle M Cylinder Head N Valve O Dowel Pin Install Cylinder Head Assembly Prior to assembly, lubricate all components with engine oil, including tips of valve stems and valve guides. Install Valve Train 1.
Reassembly Install Cylinder Head Torque Sequence 3 2 1 4 NOTE: Do not reuse cylinder head gasket. Always replace with new gasket. 1. Examine sealing surfaces of cylinder head and crankcase for nicks or burrs. 2. Using cylinder head dowels as a guide, install a new head gasket. 3. Match sides of head together and finger tighten screws. 4. Torque screws in two stages; first to 14 N·m (123 in. lb.), finally to 27.8 N·m (246 in. lb.), following sequence shown. 5. Install rocker arms onto rocker studs.
Reassembly 2. Apply a 1.5 mm (1/16 in.) bead of Permatex® Ultra Grey® sealant to valve cover as shown. Valve cover must be installed within 10 minutes of RTV application. 3. Install valve cover and finger tighten screws. 4. Using sequence shown, tighten cover screws to 8 N·m (71 in. lb.). Flywheel/Ignition/Fuel Tank Components A B C Install New Spark Plug 1. Set gap of a new spark plug to 0.76 mm (0.030 in.). 2. Install spark plug and torque to 27 N·m (20 ft. lb.).
Reassembly Install Two-Piece Breather Filter 1. Install lower breather media into cavity, then install upper breather media. 2. Install breather disc and spring. 3. Install breather cover and secure with screws. Torque screws to 10 N·m (89 in. lb.). Install Stator (if equipped) A B A Stator (if equipped) B Connects to Diode Position stator on crankcase with lead towards crankcase and routing where electric starter will be installed. Stator terminal connects to diode; move sleeving and connect terminal.
Reassembly Install Governor Assembly 1. Install governor lever onto governor shaft with lever up. 2. Attach throttle linkage and linkage spring to top of governor lever.
Reassembly Carburetor Components Install Carburetor with Auto Choke (if equipped) B E C D D A E F A B B C A Carburetor Stud(s) B Gasket and Spacer Kit C Gasket and Heat Shield Kit D Linkage C E E Carburetor Install Carburetor Gaskets Place spacer gasket, cylinder head spacer and heat deflector gasket on carburetor studs in order shown. Install Carburetor and Linkage NOTE: There are several different ways to attach carburetor linkage depending on carburetor and speed bracket used.
Reassembly 3. Connect wire choke linkage while sliding carburetor to its seated position against engine. 4. Insert screws connecting arm assembly to carburetor. Torque to 2.3 N·m (20 in. lb.). Adjust Governor Move governor lever away from carburetor to limit of its travel (wide-open throttle), and hold in this position. Do not stress, flex or distort linkage. Grasp cross shaft with a pliers and turn shaft clockwise as far as it will go, hold and tighten nut. Torque nut to 9.5 N·m (84 in. lb.).
Reassembly Install Fuel Pump (if equipped) F H C H E A C B I G D F A E A In-Nipple Fuel Filter B Fuel Pump C Screw D Inlet Fuel Line E Tee Fitting F Vent Hose G Fuel Pump Bracket H Nut I Outlet Fuel Line NOTE: If a new fuel pump is being installed, make sure orientation of new pump is consistent with removed pump. Internal damage may occur if installed incorrectly. 1. Connect vent hose to valve cover fitting. 2.
Reassembly External Engine Components A B C E D F H G I E F K O J P L M Q N A Engine Cover and Retractable Starter B Retractable Starter C Blower Housing D Lock Nut E Muffler Guard F Muffler G Exhaust Stud H Muffler Gasket (Heat Deflector) I Shoulder Screw J Spark Plug Lead K Breather Hose L Air Cleaner Base Gasket M Air Cleaner Base N Nut O Paper Element P Precleaner Q Air Cleaner Cover 66 KohlerEngines.com 14 690 10 Rev.
Reassembly Install Air Cleaner Assembly Install Engine Cover and Retractable Starter (if equipped) Install engine cover and retractable starter onto studs, secure with nuts. Torque nuts to 8 N·m (71 in. lb.). A Install Fuel Cap Screw fuel cap tightly onto fuel tank. B Prepare Engine for Operation Engine is now reassembled. Before starting or operating engine be sure to do following: 1. Make sure all hardware is properly torqued. 2. Make sure oil drain plugs are tightened securely. 3.
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