300cc 250cc 200cc Carbuor With Electrical Choke For Motorcycle Atv Utv Gokart

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The most modern carburetors are Vacuum controlled or CV (Constant Vacuum) type. A vacuum operated diaphragm controls the opening and closing of the slide (or piston). The CV Carburetor also has a butterfly throttle valve (or throttle plate). At idle, with the throttle plate closed and the air stream cut off, idle speed is maintained by fuel metered through the slow jet. Air from the slow air jet mixes with the fuel and is delivered to the idle port at the vacuum side of the throttle plate. At low speed as the throttle plate is cracked open the transfer ports are exposed to the vacuum side of the throttle plate and additional fuel is directed to the barrel of the carburetor. With throttle plate cracked open a quantity of fuel also enters the air stream from the needle jet. The idle and transfer ports supply additional fuel to the carburetor barrel to assist during the transition period from idle to mid range. The venturi opening is reduced by the low position of the vacuum piston (Slide). This enables initial air stream velocities to be higher than normally attainable with fixed venturi carburetors. The higher air stream velocities provide greater quantities of fuel necessary for good acceleration. As the throttle plate is opened, airflow increases through the carburetor and the pressure drop in the venturi near the needle jet increases. The low pressure in the venturi travels through the vacuum port in the vacuum piston to the chamber above the diaphragm. The chamber beneath the diaphragm is vented to atmospheric pressure by a passage from the chamber to the carburetor inlet. The higher pressure at the underside of the diaphragm overcomes spring pressure and moves the vacuum piston upward in proportion to the pressure difference between chambers. As the throttle plate is opened further, the pressure difference between the chambers above and below the diaphragm increases and the vacuum piston moves further upward. The venturi opening increases and the needle is lifted further out of the needle jet. The quantity of fuel and the volume of air are simultaneously increased and metered to the proportions of engine demand by the variable venturi and needle lift. The accelerator pump is used to supply fuel during sudden or rapid throttle openings. It quickly injects fuel into the venturi; the extra fuel provides for smooth acceleration and reducing throttle hesitation. For cold starting carburetors are equipped with a choke or an enrichener circuit. The choke is a flap type valve similar to the butterfly or throttle plate. It is located on the inlet side of the carburetor and reduces airflow making the fuel mixture richer. As the engine warms up the choke is opened up and the carburetor returns to normal operation. An enrichener is a separate fuel circuit, manually controlled by a cable when it is engaged it provides additional fuel making the idle mixture richer. 

300cc 250cc 200cc Carbuor