Abstract: An air valve type two-stage twin compound carburetor for an internal combustion engine comprises a carburetor body including a primary bore and a secondary bore, a primary throttle valve which is arranged in the primary bore so that it can be opened and closed, a secondary throttle valve which is arranged in the secondary throttle bore so that it can be opened and closed co-operatively with the opening and closing of the primary throttle valve after the primary throttle valve has been opened beyond a certain degree, and an air valve which is arranged in the secondary bore upstream of a secondary fuel nozzle disposed upstream of the secondary throttle valve, so that the air valve is opened and closed. The degree of opening of the air valve is regulated so as to be opened when the primary throttle valve is in the idle closing position or in the initial opening position.

Abstract: A fuel control apparatus for controlling the flow amount of fuel delivered from a carburetor having a power circuit is disclosed, in which the fuel passage of the power circuit permits the fuel in a float chamber of the carburetor from flowing toward the fuel nozzles of the carburetor in response to the reduction in the vacuum led into a vacuum chamber of the carburetor from a vacuum reservation tank in which the vacuum introduced from an intake manifold of a gasoline engine is reserved. The vacuum reservation tank has a considerable volumetric space therein defined by a sealed housing, and is disposed to the exterior of the carburetor. The fuel control apparatus also comprises a means for causing reduction in the vacuum developing in a vacuum region between the vacuum reservation tank and the vacuum chamber of the carburetor.