Abstract: Method and apparatus for controlling emissions, particularly of unburnt hydrocarbons, from a two stroke engine. The engine has direct in-cylinder fuel injection and has in the air inlet port and the exhaust port respective devices to control the flow therethrough. The devices are each independently controlled in relation to engine load demand and engine speed to regulate the mass of exhaust gases retained in the combustion chamber. The exhaust flow control device perferably also alters the timing of opening and closing of the exhaust port.

Abstract: A direct injected two stroke cycle internal combustion engine having a cylinder, a cylinder head at one end of the cylinder, a piston mounted for reciprocation in the cylinder, and an inlet port and an exhaust port in the wall of the cylinder at substantially diametrically opposite locations in the cylinder. A cavity in the cylinder head extending in a generally diametral direction from adjacent the cylinder wall at a location opposite the exhaust port. The cavity having substantially straight side edges in the direction of extension, and the longitudinal length of the cavity in said direction being about 0.55 to 0.77 of the diameter of the cylinder.