Function

As long as motorcycles are not required by law, to have an effective exhaust detoxification these are still often found among the low-performance two-wheeled vehicles, because it combines a simple design with effective function.

How it works

The amount of fuel-air-mixture is dependant on the diameter of the choke funnel. If this diameter is opened through the throttle valve by the throttle cable, more air flows into the engine. In this case, a conically shaped needle which is moved, together with the throttle valve upwards, slides less into the nozzle, thus opening the nozzle diameter and providing for an accordingly higher fuel portion. In the individual working conditions, from the low partial load range, right up to almost full load, the mixing proportion can be influenced by a certain needle-shape and height (in the throttle valve variable).

A ring float provides for a constant fuel situation in the main jet. Above the main jet, the fuel supply for the idling branches off. The mixing proportions are adjusted by the setting screw on the right (clockwise for lean, anti-clockwise for rich). The idling speed is nearly always adjusted on the throttle cable. This is where it's decided, how far the throttle valve still opens the choke funnel, when in its lowest position. 09/09