The manual says this is the process to adjust the idle or low speed mix. Adjust the idle mixture screw so that the gap between the idle mixture needle and the spray nozzle is 3/32-1/8 inch ( looking down into the carb opening). Start engine and close throttle just short of where the engine stops. Pinch the fuel line and if engine speeds up a bit the mixture is rich. Turn mix screw clockwise 1/8 turn and repeat process until no change occurs. Of course if the engine slows down when the line is pinched then the mix is too lean and you open the needle same amount and repeat. If you need a copy of this I could email. Hope this helps