Automatic Choke
Choke provides a rich mixture for cold engine and weakens the mixture gradually as the engine warms up. It increases idle speed as long as engine is not properly warm. At low temperature a bi-metal spring begins to uncoil and the movement is transmitted to the choke valve lever. This closes choke valve and engine receives a rich mixture. The movement of the choke valve shaft is transmitted to an operating lever which in turn moves the fast idle cam. When bi-metal coil is closed (cold position) the idle screw rests on the high step of the cam. During warm up and running conditions, fast idle cam turns and idle screw rests on progressively lower steps of the cam.