The main metering jet (C) supplies the amount of fuel required for high speed operation. As the carburetor throttle valve (J) is opened (beyond idle speed requirements), high velocity air passing through the carburetor throat creates a suction at the main nozzle outlet. This causes fuel to flow from the fuel bowl, through main metering jet (C) where it mixes with air from the nozzle bleed (K). This fuel air mixture passes through main nozzle (L) and into the air stream at the carburetor throat. Clockwise adjustment of the main metering screw (M), which controls the amount of fuel, leans the mixture. Maximum mixture is usually obtained with three turns open. Do not attempt to remove nozzle bleed (K).