Weak or No Spark
| Sparkplug fouled or damaged | Replace sparkplug |
| Pickup coil faulty | Replace pickup coil |
| CDI unit faulty | Replace CDI unit |
| Stator faulty or sheared woodruff key | Replace stator – inspect woodruff key |
| Ignition coil faulty | Replace ignition coil |
Spark Plug Fouled
| Air filter dirty | Clean air filter |
| Incorrect sparkplug (too cold) | Replace with correct heat range |
| Contaminated fuel | Replace fuel |
| Mixture to rich | Clean and adjust carburetor |
| Valve seals worn | Replace valve seals |
| Oil rings faulty | Replace piston rings |
Sparkplug Electrode Burnt
| Incorrect sparkplug (too hot) | Replace with correct heat range |
| Fuel mixture lean | Clean and adjust carburetor |
| Loose sparkplug | Tighten sparkplug |
| Engine overheats | Diagnose cooling system problem |
Battery Won’t Keep Charge
| Stator wires broken-shorted-bad connection | Repair or replace |
| Stator coils broken-shorted-bad connection | Repair or replace |
| Regulator/rectifier shorted-bad connection | Repair or replace |
Stator Charges, but not to Specification
| Battery faulty | Charge or replace battery |
| Regulator/rectifier faulty | Check connections or replace |
| Stator coils faulty | Check connections or replace |
| Battery lead wires loose | Check connections |
Stator Overcharging
| Regulator/rectifier faulty ground | Tighten ground connection |
| Regulator/rectifier faulty | Replace faulty regulator/rectifier |
| Battery internal short | Replace battery |
Electric Start
| Battery voltage low | Charge battery |
| On/off switch, in off position | Turn switch to the on position |
| Key not turned on | Turn key on |
| Switch contacts faulty | Check connection/clean contacts |
| Wire connections loose | Check connection/clean contacts |
| Clutch/neutral switch faulty | Test and replace faulty switch |
| Starter relay faulty | Test replace faulty starter relay |
No Electrical Power
| Main fuse faulty | Replace fuse |
| Battery low or faulty | Charge or replace battery |
| Battery terminals backwards | Reverse terminals, replace battery |