The following identifies the main components of a typical engine assembly visible from the exterior. Some variants may differ in detail. Remember that the left and right sides are determined when viewing the flywheel (rear) end of the engine.

The following identifies the main internal components of a typical engine assembly. Some variants may differ in detail.

The valve train system opens and closes the valves with correct timing in relation to the piston movements.

During the working cycle of the engine a great deal of heat is generated. It is important that the engine is kept at its normal operating temperature to achieve maximum efficiency. It is the function of the cooling system to allow the engine to reach this temperature quickly and then maintain it.