Zenith NDIX 2-Barrel: Operation: Idling
The mixture supplied to the engine under idle conditions is determined by the idle jet, idle air jet and the idle mixture screw. Fuel from the float bowl is taken by the idle jet and mixed with air from the idle air jet. This mixture flows to the mixture chamber, past the idle mixture screw, just below the throttle valve. At this point additional air entering through the throttle valve mixes with the mixture and is supplied to the engine.