FIELD: mechanical engineering; internal combustion engines. SUBSTANCE: proposed method comes to compression of fresh charge of air or fuel mixture, delivery of fresh charge into combustion chamber made in cylinder head, closing of intake hole separating fresh charge accumulation space from combustion chamber by intake valve, opening of bypass valve separating combustion chamber and cylinder working space, ignition of fuel mixture in combustion chamber, bypassing combustion products into working space from combustion chamber through bypass hole. With piston approaching bottom dead center, bypass valve moves in direction of bottom dead center overlapping by its sealing surface the bypass hole of combustion chamber and separating the chamber from cylinder working space. Intake valve opens intake hole and combustion chamber is scavenged. With piston moving towards to dead center at exhaust stroke with exhaust valve open, bypass valve opens providing scavenging of combustion chamber and cylinder working space. Moments of beginning of closing of bypass and exhaust valves after termination of scavenging are adjusted depending on engine load to provided earlier beginning of valve closing at increase in engine power and later beginning of valve closing at reduced power. Duration of period from beginning of displacement of valves from open position to stopping in closed position at any duties is maintained constant. EFFECT: improved efficiency of operation of two-stroke engine. 5 cl, 3 dwg
