Adjustable main metering screw controls fuel supply above idling speed. Turning the screw in, gives leaner mixture. Turning screw out, gives richer mixture. In adjusting, do not sacrifice power or performance for economy.
After motor has reached normal running temperature and correct idle adjustment has been made, open throttle to about 35 miles per hour engine speed. Turn metering screw OUT until motor reaches maximum speed, then IN until engine speed starts to decrease. Now open screw slowly until motor reaches maximum speed. This adjustment will give maximum power and economy.