Flywheel

The flywheel is a rotating mass attached to the crankshaft. It stores energy during each power stroke and releases it during the other strokes, smoothing out engine pulses and helping the engine idle and pull steadily. On many motorcycles the flywheel is the alternator rotor, with magnets for charging and ignition triggering.

A heavier flywheel gives a smoother, more tractable engine that is less likely to stall – useful in enduro and trials. A lighter flywheel lets the engine rev up and down faster, preferred in motocross and racing. Flywheel weights can be added to some off-road engines.

Removing a flywheel needs the correct puller; never hammer it off, as this damages the crankshaft and magnets.