Distributor (Ignition)

A distributor is a rotating switch driven by the engine. A rotor inside a cap sends the high-voltage pulse from the ignition coil to each spark plug lead in the right order. Older designs also housed the contact breaker points, condenser and a mechanical advance mechanism.

Distributors were common in cars but only appeared on some classic motorcycles. Most bikes instead used one coil per cylinder or per pair of cylinders, and modern machines use electronic ignition with no moving contacts.

On a classic bike with a distributor, check the cap and rotor for cracks and carbon tracking, and set the points gap and timing as the manual describes.