Ignition System

The ignition system produces the spark that ignites the compressed fuel-air mixture in the cylinder. It turns the low voltage from the battery or alternator into tens of thousands of volts via an ignition coil and fires it across the spark plug gap at exactly the right moment.

Old bikes used mechanical contact breaker points. Modern motorcycles use electronic ignition, either CDI (capacitor discharge ignition, common on small engines and two-strokes) or transistorised systems controlled by the engine's ECU, often with a coil directly on each plug.

Misfires, hard starting or cutting out can come from worn plugs, cracked plug caps, damaged leads, a failing coil or a faulty pickup sensor. Start with the cheapest checks: plug condition and connections.