A capacitor discharge ignition is an electronic device that stores an electrical charge and then discharges it through an ignition coil in order to produce a powerful spark from the spark plugs in a petrol engine. CDIs are commonly found on motorbikes and scooters.
CDIs are designed solely for vehicles that use a petrol engine. A CDI is comprised of several parts and is integrated with the ignition system of a vehicle. The main parts of a CDI include the stator, charging coil, hall sensor, flywheel and the timing mark. A diagram of a CDI can be found on vespamaintenance.com.