Vento Phantom R4i Service Maintenance Manual page 84

Complaint Symptom and possible causes
No sparking or 1. Defective CDI & ignition coil unit.
poor sparking. 2. Defective spark plug.
3. Defective magneto stator coil.
4. Loose connection of lead wire.
5. Defective pick-up coil
Spark plug 1. Mixture too rich.
soon becomes 2. Idling speed too high.
fouled with 3. Incorrect gasoline.
carbon. 4. Dirty element in air cleaner.
5. Spark plug loose.
6. Too cold spark plugs
Spark plugs 1. Worn piston rings.
become fouled 2. Worn piston or cylinder.
too soon 3. Excessive clearance of valve stems in valve
4. Worn stem oil seals.
Spark plug 1. Spark plug too hot.
electrodes 2. Overheated the engines
overheat or 3. Loose spark plugs.
burn. 4. Too lean mixture.
5. Not enough engine lubricating oil.
1. Open or short in lead wires, or loose lead
Magneto does
not charge the
battery. 2. Shorted, grounded or open magneto coil.
3. Shorted or open regulator/rectifier.
Magneto 1. Lead wires tend to get shorted or open-circuited
charge, but
charging rate is 2. Grounded or open-circuited stator coils of
below the
specifications. 3. Defective regulator/rectifier.
4. Defective cell plates in the battery,
Magneto 1. Internal short-circuit in the battery.
overcharges. 2. Resistor element in the regulator/rectifier
3. Regulator/rectifier unit poorly grounded.
VENTO MOTORCYCLES
ELECTRICAL
guides.
connections.
or loosely connected at terminal.
magneto.
damaged or defective.
Rev no.01/ page 84of 84
Remedy
Replace.
Replace.
Replace.
Connect/tighten.
Replace.
Adjust carburetor.
Adjust carburetor.
Change & use specified gasoline.
Clean.
Check & retighten.
Replace with hot type plugs.
Replace.
Replace.
Replace.
Replace.
Replace with specified cold plugs.
Tune up.
Retighten.
Adjust carburetor.
Check oil pump.
Repair or retighten.
Replace.
Replace.
Repair or retighten.
Replace.
Replace.
Replace the battery.
Replace the battery.
Replace.
Clean and tighten ground
connection.