Air/fuel mixture supply device for a two-stroke internal-combustion engine

Air/fuel mixture supply device for a two-stroke internal-combustion engine of the type with scavenging by compressed air in the casing, the device comprising at least one cylinder, a piston capable of reciprocating motion in the cylinder for defining a combustion chamber and a scavenging-air compression casing provided with an air inlet orifice, the cylinder comprising at least one exhaust port, at least one transfer port communicating via a transfer duct with the casing, a port for introduction of an air/fuel mixture into the combustion chamber, towards the end of the scavenging, and a rotary closure member driven in synchronism with the rotation of the engine and associated with the port for introduction of the air/fuel mixture into the combustion chamber, the device further comprising an air reservoir supplied with air under a pressure greater than the pressure prevailing in the combustion chamber after opening of the exhaust port, a venturi placed between the reservoir and the rotary closure member, and a fuel feed coming from a constant-level tank and emerging in the divergent cone of the venturi.