Engine General Information and Diagnosis: 1A-1
Engine General Information and Diagnosis
Diagnostic Information and Procedures
Engine Symptom Diagnosis
B649G11104011
Condition Possible cause Correction / Reference Item
Engine will not start or is
hard to start
(Compression too low.)
Worn cylinder. Rebore or replace.
Worn piston ring. Replace.
Worn valve guide or improper valve
seating.
Repair or replace.
Loose spark plug. Tighten.
Broken, cracked or damaged piston. Replace.
Slow cranking starter motor. See electrical section.
Mistimed valves. Adjust.
Valve clearance out of adjustment. Adjust.
Engine will not start or is
hard to start (Plugs not
sparking.)
Damaged spark plug. Replace.
Damaged spark plug cap. Replace.
Fouled spark plug. Clean or replace.
Wet spark plug. Clean and dry or replace.
Defective ignition coil. Replace.
Open or short in high-tension cord. Replace.
Defective CKP sensor. Replace.
Defective ignitor. Replace.
Engine will not start or is
hard to start (No fuel
reaching the carburetor.)
Clogged fuel tank vent hose. Clean or replace.
Clogged or defective fuel valve. Clean or replace.
Defective needle valve. Replace with needle valve seat.
Clogged fuel hose. Clean or replace.
Clogged fuel filter. Clean or replace.
Engine stalls often Fouled spark plug. Clean or replace.
Defective CKP sensor. Replace.
Defective ignitor. Replace.
Clogged fuel hose. Clean.
Clogged carburetor jet. Clean.
Valve clearance out of adjustment. Adjust.
Engine noisy (Excessive
valve chatter.)
Excessive valve clearance. Adjust.
Weak or broken valve spring. Replace.
Worn rocker arm or rocker arm shaft. Replace.
Worn or burnt camshaft journal. Replace.
Engine noisy (Noise
seems to come from
piston.)
Worn piston. Replace.
Worn cylinder. Rebore or replace.
Carbon build-up in combustion chamber. Clean.
Worn piston pin or piston pin bore. Replace.
Worn piston ring or ring groove. Replace.
Engine noisy (Noise
seems to come from
timing chain.)
Stretched cam chain. Replace cam chain and sprockets.
Worn cam chain sprocket. Replace cam chain and sprockets.
Improperly working cam chain tensioner. Repair or replace.
Engine noisy (Noise
seems to come from
clutch.)
Worn countershaft spline. Replace countershaft.
Worn clutch hub spline. Replace clutch hub.
Worn clutch plate teeth. Replace clutch plate.
Distorted clutch plate. Replace.
Worn clutch release bearing. Replace.
Weak clutch damper. Replace primary driven gear.
Engine noisy (Noise
seems to come from
crankshaft.)
Worn or burnt crank pin bearing.
Replace.
Worn or burnt journal bearing. Replace.
Excessive thrust clearance. Replace thrust bearing.
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