Idle Speed System

Each mixing chamber has its own separate idle speed system. Fuel required at idle speed is obtained from main jet system. It is metered by idle jet and mixed with air drawn in through press fit idle air jet to form an emulsion. This emulsion then passes to a bore located below throttle valve. Quantity of emulsion passing through this bore is determined by idle mixture regulating screw. This emulsion when combined with air drawn in through narrow gap of throttle valve forms an idle speed air/fuel mixture. Air by-pass bores, located above closed throttle valves, do not come into action until throttle is opened. They improve transition from idle speed to main jet system.