To perform operations starting at no-load to high-load in a 2-cylinder engine in which an air-fuel mixture is individually supplied from a duplex carburetor into cylinders.
This 2-cylinder engine is formed in such a manner that tow intake passages 2A and 2B independent of each other for individually supplying the air-fuel mixture into the cylinders 11A and 11B are connected to each other in a communication passage 7 on the downstream side of throttle valves 38A and 38B and an opening/closing valve 8 closed in an area where an intake tube negative pressure is high and opened in an area where the intake tube negative pressure is low is installed in the communication passage 7. In the 2-cylinder engine, the venturi diameter of the duplex carburetor 3 is reduced, the air-fuel mixture is individually supplied from the no-load to an intermediate load to increase no-load operability and acceleration. At high-load, the other mixture is merged to one mixture from the communication passage 7 to increase an intake amount of air so as to increase the maximum output.
Kyoko Hashimoto
Kojiro Matsushita