CDI unit is a common form of automotive electronic ignition system used in outboard motors, motorcycles, lawn mowers, chainsaws, small engines, turbine-powered aircraft, and some cars. It is also known as capacitor discharge ignition or thyristor ignition. Our offering regulates the ignition system of a motorcycle by initiating the ignition and combustion process. CDI unit is plugged with spark plug which is ignited by a pulse of electricity from the motorcycle battery. Check the continuity of the ground at all of the different sites. If your device is functioning properly, there shouldn't be any noises.