Normally I would set the mixture screw at 1-1/2 turns out (gently screw it fully in until you feel it stop,then screw it out). and the the throttle-stop screw about a couple of turns--enough to give it a fastish idle when the engine is warm. With engine warm, lower the idle speed to the lowest smooth, steady idle. Turn the mixture screw in until the idle goes rough, and then turn it back out until the engine is running smoothly again. If the idle speed is incorrect, adjust it with the throttle-stop screw, and then again adjust the mixture with the mixture screw. The idle speed is about 800rpm---if you have a dynamo on the engine, the ignition light will still be on, just. Other people will have their own method, but this as basically the method described in the 'factory' work-shop manual.
