The engine starter motor is a powerful electric motor used to start the engine. 

The starter motor has a small gear that meshes with the teeth on the engine flywheel and rotates the crankshaft.

The starter motor of a motorcycle is the core component of the electric start system, which is used to drive the engine crankshaft to rotate by electricity, thereby starting the engine.

Main components
- ** Motor body **: Contains the armature, field coil, and carbon brush, which are responsible for converting electrical energy into mechanical energy.
- ** Gear mechanism **: Includes the pinion (drive gear) and the one-way clutch, which are used to transmit the rotational force of the motor to the engine crankshaft.
- ** Electromagnetic switch (relay) **: Controls the start and stop of the motor and at the same time pushes the pinion to engage with the engine flywheel.
- ** Casing **: Protects internal components, usually made of metal, with good heat dissipation and durability.