Solenoid (starter solenoid)

A solenoid is a coil of wire that becomes an electromagnet when current flows through it, pulling a metal plunger. That movement can close heavy electrical contacts or move a mechanical part.

On a motorcycle the best-known example is the starter solenoid (starter relay). Pressing the starter button sends a small current to the solenoid, which then connects the battery directly to the starter motor through thick cables. Solenoids are also used in fuel injectors, exhaust and intake valves on some bikes, and shift actuators.

A single click and no cranking can mean a weak battery, a bad connection or a worn solenoid. Check the battery and terminals first, then test the solenoid.