Abstract: A two-cycle engine has an air inlet in the crankcase, and a spiral air-fuel passage encircling the cylinder wall rising from the crankcase to an inlet in the cylinder head to effect cooling of the cylinder. A fuel injection device introduces fuel into the transfer passage. A unidirectional valve admits air and fuel into the cylinder head and curved fins impart a swirling action to the air and fuel to effect a fuel and air stratification. An exhaust passage in the cylinder wall has an adjustable throttle to control dirctly the outflow of exhaust gases and indirectly the inflow of fresh fuel-air mixture, whereby the power level of the engine is controlled.

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.

Abstract: A two cycle, spark ignition internal combustion engine of the class having a combustion chamber divided into a relatively small ignition region and a larger combustion region including the cylinder and piston is defined. Substantially stoichiometric fuel-air mixtures are independently supplied to the ignition region in substantially fixed quantity and to the larger region in variable quantity and compressed simultaneously so that the mixtures remain completely separated prior to ignition. The mixtures are stratified with respect to excess air supplied to both regions and to exhaust gases in the engine cylinder, and combustion initiated in the ignition region ignites the variable-sized mixture in the larger region. Burning proceeds from stoichiometric mixtures to lean mixtures as the stratified excess air is mixed into the burning gases. When no fuel is supplied to the large region, the small region functions independently and burns its fuel efficiently.