Motorcycle Repair: starting, shovel head, big twin evo

Question
try to start it just whinds and spins untill catches and starts

Answer
If the bike your working on is an electric start Harley Davidson of the sporty, big twin evo or shovel head era. Your problem is probably the starter drive also called a starter bendix. Its a small one way gear mounted on a shaft that turns the clutch shell to rotate the engine and start it. The gear is only suppose to turn in one direction but when they start to wear out they will sometimes rotate in both directions and occasionally start the bike usually proceeded by a whine then bike starts to eventually it won't catch to start the bike at all. If you working on anything else I have no idea what the problem might be.