5. FUEL SYSTEM ATV 50 AIR SCREW ADJUSTMENT Air Screw Turn the air screw clockwise until it seats lightly and back it to the specification given. Do not force the air screw against its seat to prevent damage. Start the engine and turn the air screw in or out slowly to obtain the highest engine speed. Throttle Stop Screw Turn the throttle stop screw to obtain the specified idle speed. Idle Speed: 1800100 rpm Air Screw Opening: 2 1/2 turns Slightly increase the engine speed and make sure that the engine does not miss or run erratic. If the adjustment of the air screw within the range of 1/2 turn makes no difference to the engine performance, check other related items. 5-12