Capacitor discharge ignition (CDI) is an electronic ignition module widely used in motorcycles, outboard motors, and small engines. The system charges a capacitor to a high voltage and then rapidly discharges it through the ignition coil to fire the spark plug. This creates a very intense but short-duration spark that resists fouling and provides reliable starting at high RPMs.
Heard on the job
If you have no spark on that dirt bike, test the stator output before you just throw a new CDI box at it.
Insider tip
A failing CDI often causes intermittent spark issues that worsen as the engine gets hot.
Also heard as
- capacitor discharge ignition