Abstract: A two-cycle internal combustion engine having an "open" combustion chamber/poppet valve arrangement that produces improved scavenging. The combustion chamber has a generally oblate configuration and is slanted with respect to the cylinder axis in such a manner that the air flowing therein converges and is directed downward in a collimated column into the cylinder. The placement of overhead cam operated poppet valves in combination with the combustion chamber produces a scavenging method of the reverse return-flow type. A displacer piston having a displacer with a peripheral wall corresponding in configuration to that of the combustion chamber and defining a recess of predetermined volume that forms the floor of the combustion chamber when the piston is located in its upper most position may be advantageously employed.

Abstract: A two-cycle internal combustion engine having an "open" combustion chamber/poppet valve arrangement that produces improved scavenging. The combustion chamber has a generally oblate configuration and is slanted with respect to the cylinder axis in such a manner that the air flowing therein converges and is directed downward in a collimated column into the cylinder. The placement of overhead cam operated poppet valves in combination with the combustion chamber produces a scavenging method of the reverse return-flow type. A displacer piston having a displacer with a peripheral wall corresponding in configuration to that of the combustion chamber and defining a recess of predetermined volume that forms the floor of the combustion chamber when the piston is located in its upper most position may be advantageously employed.