Abstract: A crankcase scavenged two-stroke internal combustion engine (1) in which a piston ported air passage is arranged between an air inlet (2) and the upper part of a number of transfer ducts (3, 3?). The air inlet is equipped with a restriction valve (4), controlled by at least one engine parameter, for instance the carburetor throttle control. The air inlet extends via at least one connecting duct (6, 6?) to at least one connecting port (7, 7?) in the engine's cylinder wall (12). The connecting port (7, 7?) is arranged so that when the piston is in a top dead center configuration, it is connected with flow paths (9, 9?) embodied in the piston (13).

Abstract: Crankcase scavenged two-stroke internal combustion engine (1), in which a piston ported air passage is arranged between an air inlet (2) and the upper part of a number of transfer ducts (3, 3?). The air passage is arranged from an air inlet (2) equipped with a restriction valve (4), controlled by at least one engine parameter, for instance the carburetor throttle control. The air inlet extends via at least one connecting duct (6, 6?) to at least one connecting port (8, 8?) in the engine's cylinder wall (12). The connecting port (8, 8?) is arranged so that it in connection with piston positions at the top dead center is connected with flow paths (10, 10?) embodied in the piston (13), which extend to the upper part of a number of transfer ducts (3, 3?).

Abstract: Crankcase scavenged two-stroke internal combustion engine (1), in which a piston ported air passage is arranged between an air inlet (2) and the upper part of a number of transfer ducts (3, 3?). The air inlet is equipped with a restriction valve (4), controlled by at least one engine parameter, for instance the carburettor throttle control. The air inlet extends via at least one connecting duct (6, 6?) to at least one connecting port (7, 7?) in the engine's cylinder wall (12).

Abstract: Crankcase scavenged two-stroke internal combustion engine, in which at least one piston ported air passage, with length Lai, is arranged between an air inlet (2) and each scavenging port (31, 31′) of a number of transfer ducts (3, 3′), with length Ls, from the scavenging port to the crankcase. The air passage is arranged from an air inlet (2) equipped with a restriction valve (4), controlled by at least one engine parameter, for instance the carburetor throttle control. The air inlet extends via at least one connecting duct (6, 6′) to at least one connecting port (8, 8′) in the engine's cylinder wall (12). The connecting port (8, 8′) is arranged so that it in connection with piston positions at the top dead center is connected with flow paths (10, 10′) embodied in the piston (13), which extend to the upper part of a number of transfer ducts (3, 3′).

Abstract: A two-stroke internal combustion engine comprising a cylinder (10; 50) with a movable piston (11; 52) in it, which cylinder at its one end has a combustion chamber (16; 51) and at its other end is connected to a crankcase (15; 53). The crankcase and the combustion chamber are mutually connected via a scavenging duct (17; 56), whose opening and closing is controlled by the movement of the piston, and a carburetor (20; 55) is via an inlet port (21) connected to the crankcase. In order to simplify starting the engine it is provided with a device (23-6; 61-65; 70-72) for supply of fuel to the scavenging duct (17; 56) adjacent the combustion chamber.