The features of this engine are as follows: two cylinders are arranged in parallel and a common combustion-chamber is used. Two pistons move up and down synchronously. One cylinder is only provided with a scavenging port and the other cylinder is only provided with an exhaust port. The combustible mixed gas is fed from an inlet port into crankcase and through the scavenging port into one cylinder, and then through the common combustion-chamber into the other cylinder, so that the waste gas in the cylinder is discarged from the exhaust port. The main advantages of this engine is that it can decrease the loss of the combustible mixed gas and its economy efficiency is better than that of original two-stroke gasoline engine. |