Abstract: A two-cycle internal combustion engine is described having a combination of a combustion chamber portion at one end of the cylinder for receiving predetermined amounts of air and fuel; inlet ports for injecting fuel and compressed air into the upper end of the combustion chamber portion; exhaust ports in the cylinder for the conduction of exhaust gases and air from the combustion chamber portion, said exhaust port means being covered and uncovered by the side of the piston means and positioned to be fully uncovered at the bottom dead center position of the piston; a fuel/air mixing system in communication with the inlet ports the system having an air supply for providing a continuous supply of compressed air to the combustion chamber portion, a supply of compressed air generated by the engine, a fual supply for providing predetermined quantities of fual at specified intervals, and, a precombustion chamber for receiving and mixing the compressed air and the predetermined quantities of fuel and providing the co