Abstract: A two-stroke internal combustion engine is provided with a cylinder and a piston reciprocatingly mounted in the cylinder; the cylinder has two inlet ducts each having a inlet port opening into the cylinder for delivering a inlet strain to the cylinder and an exhaust duct having an exhaust port opening in the cylinder for removing an exhaust product from the cylinder with the inlet ducts and ports disposed so that the inlet stream impacts the wall of the cylinder at a substantially identical location between the exhaust port and an end of the cylinder opposite the piston with the inlet ports and exhaust ports arranged to eliminate crossing of the inlet streams and the exhaust stream.

Abstract: Process and device for supplying air to the cylinder of a two-stroke internal combustion engine, with at least one set of two cylinders arranged at 180 degrees, supercharged by a post-filling effect. Said device is characterized in that it comprises a volumetric pimp defined by the natural movement of a piston between its top dead center and its bottom dead center and inversely, connected to intake air transit means (8A, 8B) for the air supply thereto. Advantageously the volumetric pump is formed by the pump casing of the cylinder which is in the scavenging phase. In a variant, this device comprises at least one transfer passage (30) intermittently connecting the transit means (8A, 8B) with the upstream pump casing (6B, or 6A) associated therewith. The device of the invention provides, at all times, the required aie supply and hence correct operation of the engine even at low loads or during start-up, and in an easy manner.