Abstract: An air-fuel ratio control device for an internal combustion engine equipped with a plurality of variable venturi type carburetors each having a slow system, in which the flow rate of air supplied to the slow systems of the carburetors is controlled depending on the engine operation parameters including, for example, the temperature of intake air, temperature of engine oil and atmospheric pressure to improve the rate of atomization of fuel, thereby improving the idling performance of the engine and therefore improving the fuel consumption of the engine.

Abstract: A throttle valve linkage for use with a multi-carburetor assembly comprising a pair of carburetors has first and second levers secured respectively to the throttle shafts of the first and second carburetors, first and second link members respectively connected at one ends to the free ends of the first and second levers. The other ends of the first and second link members are pivotally connected by a common pivot pin which is slidably movable in a guide channel. The rotation of the first carburetor throttle shaft is transmitted by the linkage to the second carburetor throttle shaft so that the latter is rotated in a direction opposite to the direction of rotation of the first carburetor throttle shaft.

Abstract: A carbureter for use in an internal combustion engine wherein a rotary throttle valve provided therethrough in the radial direction of the rotary shaft with a gasified fuel-air mixture passageway is provided in an air supply duct of the carburetor and the flow of mixtures of gasified fuel and air that is supplied into the engine can be controlled by the rotation of said rotary throttle valve, while said rotary throttle valve stays at a low opening degree, a bypass passageway forking from the intermediate portion of a low speed fuel passageway is made open to said gasified fuel-air mixture passageway and at the same time the upstream portion of the air supply duct of said rotary throttle valve and said gasified fuel-air mixture passageway can be communicated through an air passageway and while said rotary throttle valve is moved from the position "close" toward "open," predetermined interrelations are given to the opening positions or the sizes of port diameters of said gasified fuel-air mixture passageway, of