The air filter
The air filter stops dust and dirt entering the engine. A clogged filter restricts airflow, which can hurt performance and fuel economy. A damaged one lets dirt in and wears the engine.
- Check it at the interval in the owner’s manual, and more often if you ride on dusty roads or off-road.
- Paper filters are replaced when dirty. Some foam or reusable filters are cleaned and re-oiled with the products the manufacturer recommends.
- Make sure it is seated properly and the airbox is closed after you check it.
Spark plugs
Spark plugs ignite the fuel and air mixture. Worn or fouled plugs can cause hard starting, rough running or misfires.
- Replace them at the interval in the manual, and use the type and heat range it specifies.
- When removed, the colour and condition of the plug can show how the engine is running. If it looks unusual, ask a mechanic.
- Fit them with the correct torque, because over-tightening can damage the threads in the cylinder head.
Signs to check them
- Hard starting or a rough, uneven idle.
- Loss of power, hesitation or higher fuel use.
- Black smoke, a strong smell of fuel or an engine warning light.
Procedures differ by model. If you are not confident, have a mechanic do this work, and follow your owner’s manual.