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Kohler CH20S Troubleshooting

Engine Model: Kohler Command CH20S
Engine Type: 4-cycle V-Twin cylinder gasoline engine
Total Displacement: 28 (624 cc)
Rated Engine Power: 20.5 Hp (15.3 kW) at 3600 rpm
Carburetor Type: One-barrel, fixed main jet


Engine will not start or starts up hard

No gasoline in tank - Fill gasoline up.
Wrong fuel grade - Use correct fuel grade.
Air in fuel tank - Bleed fuel tank.
Spark plug wire is disconnected or loose - Inspect spark plug wiring connection, change or repair.
Damaged spark plug - Install new spark plug.
Fuel filter is plugged - Fuel filter needs to be replaced.
Faulty safety switch - Change damaged switch.
Carburetor not adjusted - Adjust according to instructions.
Poor cylinder compression - Check cylinder block and change worn parts.
Not adjusted or damaged throttle cable - Adjust correctly or change the cable.

Engine runs irregularly

Cooling fins are clogged - Wash or clean as required.
Ignition system problems - Test ignition and replace failed parts.
Defective or stuck throttle cable - Clean or change the cable.
Air filter is dirty - Change or service air filter.
Clogged or defective fuel pump - Test fuel pump and change if necessary.

Engine starts but then shuts off

Spark plug is damaged - Replace spark plug.
Clogged or defective carburetor - Clean or replace carburetor.
Defective ignition coil - Install a new ignition coil.
Broken or loose valve springs - Replace valve springs.
Valves are stuck - Service the valves.

Engine keeps overheating

Insufficient engine oil - Need to add engine oil.
Excessive engine load - Load reducing required.
Air intake grill is clogged - Wash or clean as required.
Carburetor mixture is too lean - Set the carburetor properly.
Wrong ignition timing - Ignition timing needs to be set properly.
Valve setting is incorrect - Adjust valves correctly.

Engine noise or knocking

Stale or low octane fuel - Use correct fuel.
Engine overloaded - Reduce the load.
Engine oil level low - Checking oil level and add if necessary.
Low idle speed setting is not correct - Correct idle adjustment.
Fuel pump is defective or dirty - Check fuel pump and change if required.
Worn main bearings or crankshaft - Change defective components as required.
Incorrect valve clearance - Need to adjust valve clearance.
Piston rings or cylinder bore are worn - Replace faulty components.

Low engine power

Improperly adjusted or dirty carburetor - Clean or correctly adjust carburetor.
Air filter is dirty - Clean or change air filter.
Fuel pump is dirty or defective - Test fuel pump and replace if necessary.
Ignition system malfunction - Inspect ignition system and change failed components.
Cylinder head gasket is defective - Install new head gasket.
Burned or stuck valves - Change or service valves.
Damaged or worn push rod - Change push rod.
Damaged cylinder block parts - Change defective parts.
Oil filter element is clogged (if equipped) - Replace or service oil filter.

Engine uses too much fuel

Choke doesn't open well - Adjust or replace choke cable.
Improper adjustment of carburetor main jet - Adjust it correctly.
Spark plug is defective or loose - Spark plug need to be replaced or tightened.
Burned, worn, or stuck valves - Replace or clean valves.
Sleeve, piston, or rings are damaged - Replace defective parts.
Valve clearance is not correct - Adjust valve clearance.

High engine oil consumption

Defective seals or gaskets - Replace defective parts.
Damaged valve guides or valve stems - Replace the valves.
Stuck or worn piston rings - Piston rings replacement required.
Cylinder liner or piston is scuffed - Check liner and piston, change as required.
Breather hose or pipe is blocked - Clean or replace.