Troubleshooting

Troubleshooting is the process of finding why a motorcycle, scooter or ATV is not working as it should. The key is to work systematically and change one thing at a time, rather than replacing parts at random.

A logical order for an engine that will not start or runs badly:

• basics: kill switch, side stand switch, gear in neutral, fuel in the tank, battery voltage;
• fuel: fuel tap, pump, filter, blocked carburettor jets;
• spark: spark plug condition, plug cap, ignition coil;
• air: air filter, intake leaks;
• compression: worn piston rings or valves.

Note when the fault appears (cold, hot, in rain, at certain revs), check fault codes on fuel-injected bikes and use the service manual's diagnostic tables.