Capacitor (Condenser)

A capacitor is an electrical component that stores a small amount of charge and releases it very quickly. In older motorcycle ignition systems with contact breaker points it is called a condenser: it absorbs the surge when the points open, which reduces arcing and helps the ignition coil produce a strong spark.

Modern bikes use capacitors inside the CDI ignition unit, where a charged capacitor is discharged through the coil to create the spark, and in electronics to smooth voltage. Some small off-road bikes without a battery can also run a capacitor to steady the supply for fuel injection and lights.

A failing condenser on a points ignition causes burnt points, a weak spark, misfiring and poor starting. It is a cheap part and is often replaced together with the points.