Harley-Davidson Softail Carb Carburetor Fuel System Service Manual
The carburetor is a constant velocity, gravity fed type with a float operated inlet valve, a variable venturi, a throttle stop screw for idle speed adjustment and a fuel enrichment sys tem for starting.
Idle and transfer ports provide a balanced fuel mixture during the transition period from stop to mid-range. A vacuum piston controls venturi opening.
The carburetor is specifically designed to control exhaust emissions. All jets are fixed. The idle mixture has been pre set at the factory.
The idle mixture screw is recessed in the carburetor casting. The opening is sealed with a plug because it is intended that the idle mixture be non-adjustable.
Adjusting mixture setting by procedures other than specified in this section may be in violation of Federal or State regula tions.
The carburetor has a drain for emptying the float chamber during seasonal or extended storage periods. To drain, loosen float bowl drain screw. Fuel will drain from bowl through overflow hose.
The carburetor is equipped with an accelerator pump. The accelerator pump system uses sudden throttle openings (rapid accelerations) to quickly inject fuel into carburetor venturi to provide extra fuel for smooth acceleration.