In a two-stroke cycle engine the air for scavenging and combustion is drawn into the crank-chamber and compressed in the usual way. Air admitted into the cylinder at the end of the exhaust stroke is compressed on the following stroke into chambers formed by the deflector and the projection in the cylinder head.
The highly compressed air in the chamber is used to inject fuel entering through the valve in the passage into the larger compartment of combustion chamber. The fuel is admitted through a pipe and is controlled by a governor operated valve. A similar arrangement can be used for dividing the cylinder in a four-stroke cycle engine.