TROUBLESHOOTING 3-9
ELECTRICAL
Complaint Symptom and possible causes Remedy
No sparking or poor
sparking
• Defective ignition coil/plug cap
• Defective spark plug
• Defective CDI unit
• Defective magneto
• Open-circuited wiring connections
Replace
Replace
Replace
Replace
Check and repair
Spark plug soon
become fouled with
carbon.
• Mixture too rich
• Idling speed set too high
• Incorrect gasoline
• Dirty air cleaner element
• Too cold spark plug
Carburetor tuning
Adjust throttle stop screw
Change
Replace
Replace with hot type plug
Spark plug become
fouled too soon.
• Worn piston ring
• Worn piston or cylinder
• Excessive clearance of valve stems in valve guides
• Worn stem seals
Replace
Replace
Replace
Replace
Spark plug elec-
trodes overheat or
burn
• Too hot spark plug
• Overheated the engine
• Loose spark plug
• Too lean mixture
Replace with cold type plug
Tu n e u p
Retighten
Carburetor tuning
Magneto does not
charge.
• Open- or short-circuited lead wires, or loose lead
connections
• Short-circuited, grounded or open stator coil
Repair or replace
Replace
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