The adjustments on the idle needle are very slight, 1/8 of a turn at a time. Run your motor up, and blow out all of the excess fuel. Let it idle for 30 seconds (by the watch) and advance the throttle. If it sputters and hesitates, it is too rich. If it cuts out it is too lean. Adjust the screw in for rich and out for lean (remember 1/8 turn at a time) and repeat procedure. This can be very time consuming but you will eventually get your engine performing correctly.