Schwungrad

A flywheel is a heavy disc bolted to the crankshaft that smooths the engine's rotation and stores rotational energy.

Its mass evens out the pulses of each combustion stroke for steady running, provides the friction face for the clutch, and carries the ring gear the starter engages.

The flywheel sits at the rear of the engine between the crankshaft and the clutch. The correct flywheel matches the engine and the clutch.