1 CH18- ch25 , ch620 - ch730 , ch740 , CH750 Service Manual2 Safety3 Maintenance5 Specifi cations15 Tools and Aids18 Troubleshooting22 Air Cleaner/Intake23 Fuel System29 Governor System31 Lubrication System33 Electrical System49 Starter System58 Clutch60 Disassembly/Inspection and Service75 ReassemblyIMPORTANT: 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 690 06 Rev. 690 06 Rev. 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 : is used to notify people of important installation, operation, or maintenance information.
2 WARNINGE xplosive Fuel can cause fi res and severe not fi ll fuel tank while engine is hot or 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 ames. Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Never use gasoline as a cleaning agent. WARNINGR otating Parts can cause severe away while engine is in hands, feet, hair, and clothing away from all moving parts to prevent injury. Never operate engine with covers, shrouds, or guards removed. WARNINGC arbon Monoxide can cause severe nausea, fainting or inhaling exhaust exhaust gases contain poisonous carbon monoxide. Carbon monoxide is odorless, colorless, and can cause death if inhaled. WARNINGA ccidental Starts can cause severe injury or and ground spark plug lead(s) before working on engine or equipment, disable engine as follows: 1) Disconnect spark plug lead(s).
3 2) Disconnect negative ( ) battery cable from battery. WARNINGHot Parts can cause severe not touch engine while operating or just after operate engine with heat shields or guards removed. WARNINGC leaning Solvents can cause severe injury or only in well ventilated areas away from ignition cleaners and solvents are extremely fl ammable. Follow cleaner manufacturer s warnings and instructions on its proper and safe use. Never use gasoline as a cleaning agent. CAUTIONE lectrical Shock can cause not touch wires while engine is running. CAUTIOND amaging Crankshaft and Flywheel can cause personal improper procedures can lead to broken fragments. Broken fragments could be thrown from engine. Always observe and use precautions and procedures when installing fl ywheel. CAUTIONF ailure to utilize or reassemble debris screen as designed could result in debris screen failure and serious personal injury.
4 WARNINGU ncoiling Spring can cause severe safety goggles or face protection when servicing 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 690 06 Rev. INSTRUCTIONS WARNINGB efore working on engine or equipment, disable engine as follows: 1) Disconnect spark plug lead(s). 2) Disconnect negative ( ) battery cable from battery. Accidental Starts can cause severe injury or and ground spark plug lead(s) before maintenance, replacement or repair of emission control devices and systems may be performed by any repair establishment or individual; however, warranty repairs must be performed by a Kohler authorized SCHEDULEW eekly Check heavy-duty air cleaner Cleaner/IntakeEvery 25 Hours or Annually Service /replace low-profi le Cleaner/IntakeEvery 100 Hours or Annually Replace low-profi le air cleaner Cleaner/Intake Change oil.
5 Lubrication System/Clutch Remove cooling shrouds and clean cooling Cleaner/Intake Check oil cooler fi ns, clean as necessary (if equipped).Lubrication SystemEvery 200 Hours Change oil fi System Replace fuel fi 250 Hours Replace heavy-duty air cleaner element and check inner Cleaner/IntakeEvery 500 Hours Replace heavy-duty inner air cleaner Cleaner/Intake Replace spark plugs and set SystemEvery 500 Hours2 Have crankshaft spline Perform these procedures more frequently under severe, dusty, dirty Have a Kohler authorized dealer perform this PARTSK ohler genuine Service parts can be purchased from Kohler authorized dealers. To fi nd a local Kohler authorized dealer visit or call 1-800-544-2444 ( and Canada).Maintenance424 690 06 Rev. RECOMMENDATIONS We recommend use of Kohler oils for best performance.
6 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. FUEL RECOMMENDATIONS WARNINGE xplosive Fuel can cause fi res and severe not fi ll fuel tank while engine is hot or 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 ames. Spilled fuel could ignite if it comes in contact with hot parts or sparks from ignition. Never use gasoline as a cleaning : E15, E20 and E85 are NOT approved and should NOT be used; effects of old, stale or contaminated fuel are not must meet these requirements: Clean, fresh, unleaded gasoline.
7 Octane rating of 87 (R+M)/2 or higher. Research Octane Number (RON) 90 octane minimum. Gasoline up to 10% ethyl alcohol, 90% unleaded is acceptable. Methyl Tertiary Butyl Ether (MTBE) and unleaded gasoline blend (max 15% MTBE by volume) are approved. Do not add oil to gasoline. Do not overfi ll fuel tank. Do not use gasoline older than 30 engine will be out of Service for 2 months or more follow procedure Add Kohler PRO Series fuel treatment or equivalent to fuel tank. Run engine 2-3 minutes to get stabilized fuel into fuel system (failures due to untreated fuel are not warrantable).2. Change oil while engine is still warm from operation. Remove spark plug(s) and pour about 1 oz. of engine oil into cylinder(s). Replace spark plug(s) and crank engine slowly to distribute Disconnect negative (-) battery Store engine in a clean, dry cations524 690 06 Rev.
8 Dimensions with Low-Profi le Air CleanerDimensions in millimeters. Inch equivalents shown in [ ].Specifi cations624 690 06 Rev. SHIFT [.613]SPARK [ ]PRIMARY AIR FILTER ELEMENT [ ]SAFETY AIR FILTER ELEMENT [ ]AIR FILTER COVER ASSEMBLY [ ] [ ] [ ] [ ]AIR FILTER RAIN CAP [ ]OIL FILL LOCATIONPULSE FUEL [.618]OIL FILTER [ ] [ ] [ ]CRANKSHAFTMOUNTING HOLE A ENGINE3/8-16 UNC 2B [.750]1/4 IN. SQ [ ] [ ] [ ]OIL [ ]1/4 IN. SQ KEYWAY [ ]7/16-20 UNF 2B (INCH) ( ) [ ] [ ] [ ] [ ]ENGINE MOUNTING [ ]ENGINE MOUNTING SURFACE7/16-14 UNC 2B (INCH) [.827] [ ] UNC 2B (INCH) [.669] [ ] [ ] [ ]30 30 [ ]2X OIL DRAIN PLUG 3/8 NPT (INCH)MOUNTING HOLE A [ ]LIFT [ ]Engine Dimensions with Heavy-Duty Air CleanerDimensions in millimeters. Inch equivalents shown in [ ].Specifi cations724 690 06 Rev.
9 IDENTIFICATION NUMBERSK ohler engine identifi cation numbers (model, specifi cation and serial) should be referenced for effi cient repair, ordering correct parts, and engine .. ch620 Command EngineHorizontal ShaftNumerical DesignationSpecifi cation .. ch620 -0001 Serial .. 4323500328 Year Manufactured Code Factory Code Code Year 43 2013 44 2014 45 2015 GENERAL SPECIFICATIONS3,6CH18/CH20/CH22/ ch620 /CH 621/CH640/CH641CH22/CH23/CH6207/CH6407/C H670/CH680CH25/ ch730 /CH740CH750 Bore77 mm( in.)80 mm( in.)83 mm ( in.)Stroke67 mm ( in.)69 mm( in.)Displacement624 cc(38 cu. in.)674 cc(41 cu. in.)725 cc(44 cu. in.)747 cc(46 cu. in.)Oil Capacity (refi ll) L ( qt.)Maximum Angle of Operation (@ full oil level)425 TORQUE SPECIFICATIONS3,5CH18/CH20/CH22/ ch620 /CH 621/CH640/CH641CH22/CH23/ ch620 /CH640/CH6 70/CH680CH25/ ch730 /CH740CH750 Blower Housing and Sheet MetalM5 N m (55 in.)
10 Lb.) into new N m (35 in. lb.) into used holesM6 N m (95 in. lb.) into new N m (65 in. lb.) into used holesCarburetor and Intake ManifoldIntake Manifold Mounting Fastener (torque in 2 increments)fi rst to N m (66 in. lb.)fi nally to N m (88 in. lb.)M6 Mounting N m (55-65 in. lb.)Adapter (for Heavy-Duty Air Cleaner) Mounting N m (65 in. lb.)Closure N m (216 in. lb.)3 Values are in Metric units. Values in parentheses are English equivalents. 4 Exceeding maximum angle of operation may cause engine damage from insuffi cient Lubricate threads with engine oil prior to 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 ch620 /CH640 engines changed from 624cc to 674cc; displacement can be confi rmed on engine cations824 690 06 Rev.