102 TROUBLESHOOTING GUIDE
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Fuel/air mixture inc
orrect:
•
Idle adjusting screw improperly adjusted
•
Pilot jet or air passage clogged
•
Aircleanereleme
nt clogged, poorly sealed, or not
installed
Compression low:
•
Spark plug loose
•
Cylinder head insufficiently tightened
•
Cylinder or pis
ton worn
•
No valve cleara nc e
•
Crankshaft oil seal leak
•
Valvespringbrokenorweak
•
Valve not seating properly (valve bent, worn, or
carbon accumulation on the seating surface)
•
Piston ring worn, weak, broken, or sticking
•
Piston ring side clearance excessive
•
Cylinder head gasket damaged
•
Cylinde
r head warped
•
Cylinder gasket damaged
Poor lo
w-speed performance -
Spark weak:
•
Spark plug dirty, broken, or gap improperly ad-
justed
•
Spark plug cap or high-tension wiring defective
•
Spark plug cap shorted or not contacting properly
•
Spark plug type incorrect
•
Igniter defective
•
I
gnition coil defective
•
Crankshaft sensor defective
•
Flywheel magneto defective
•
Wiring connector not in good contact
Fuel/air m ixture inc
orrect:
•
Idle adjusting screw improperly adjusted
•
Pilot jet, needle jet or air passage clogged
•
Aircleanereleme
nt clogged, poorly sealed, or not
installed
•
Choke valve closed
•
Carburetor fuel l
evel too high or too low
•
Fuel tank cap air vent obstructed
•
Carburetor holder loose
•
Air cleaner duct loose
•
Fuel tap clogged
Compression low:
•
Spark plug loose
•
Cylinder head insufficiently tightened
•
Cylinder or piston worn
•
No valve cle aran ce
•
Valve spring broken or weak
•
Valve not seating properly (valve bent, worn, or
carbon accumulation on the seating surface)
•
Piston ring worn, weak, broken, or sticking
•
Piston ring side clearance excessive
•
Cylinder head gasket damaged
•
Cylinder head warped
•
Cyli
nder gasket damaged
•
Decompression trouble
Other:
•
Igniter defective
•
Brake dragging
•
Clutch slipping
•
Engine over heating
•
Engine oil level too high