Zenith 34 VNN 1-Barrel: Operation

At cold start, choke control closes the spring loaded choke valve. At the same time, a linkage rod opens the throttle flap, ensuring sufficient idle speed. At idle, fuel passes through idle jet and duct to orifice of air mixture screw. Air/Fuel mixture is then introduced to the intake manifold. During high speed operation, throttle valve is opened and from main jet fuel passes through metering block into the throat of carburetor. There it is vaporized and drawn into the intake manifold.