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 vaporized fuel controller for a carburetor which utilizes the negative pressure in the intake manifold and electromagnet to actuate a changeover valve so as to connect the gas chamber of the float chamber to the inner vent when the engine is running, and to the canister when the engine is not running. With this invention, when the negative pressure in the intake manifold decreases while the engine is running at high speeds, the electromagnet keeps the valve from being moved by the spring force and maintains the valve at a position such that the vapor fuel is supplied to the intake manifold through the inner vent.

Abstract: An adjusting screw of a carburetor comprising a threaded portion, an enlarged head portion and a reduced diameter portion located therebetween. A thin hollow cylindrical wall is formed on a link lever of the carburetor. After the adjusting screw is screwed into the threaded hole of the hollow cylindrical wall, the reduced diameter portion of the adjusting screw is cut. Then, the top portion of the hollow cylindrical wall is bent inward for irremovably fixing the adjusting screw onto the link lever.

Abstract: A carburetor for internal combustion engines includes an inner vent passage through which the space on the free surface of liquid fuel in a float chamber is communicated with the intake passage of the carburetor and an outer vent passage through which the space in the float chamber is communicated with a charcoal canister adapted to store the fuel vapor coming from the space in the float chamber. A valve is movable between a first position in which the inner vent passage is closed and the outer vent passage is opened and a second position in which the inner vent passage is opened and the outer vent passage is closed. A pressure responsive valve actuator is operative in response to the vacuum in the intake passage to normally bias the valve to the first position and to move the valve to the second position when a vacuum is established in the intake passage. A further valve is diposed to control the connection and disconnection between the pressure responsive valve actuator and the intake passage.

Abstract: A carburetor for internal combustion engines includes an inner vent passage through which the space on the free surface of liquid fuel in a float chamber is communicated with the intake passage of the carburetor and an outer vent passage through which the space in the float chamber is communicated with a charcoal canister adapted to store the fuel vapor coming from the space of the float chamber. A valve is movable between a first position in which the inner vent passage is closed and the outer vent passage is opened and a second position in which the inner vent passage is opened and the outer vent passage is closed. A pressure responsive valve actuator normally holds the valve in the first position and moves the valve to the second position as a vacuum is generated in the intake passage. A further valve actuator holds the valve in the second position regardless of the action of the pressure-responsive valve actuator on the valve when the throttle valve has been opened to and beyond a predetermined opening.