1 Remove the carburetor cover by removing the screw. 2  Pull off the fuel diaphragm gasket. 3  Turn the carburetor over and remove the primer bulb by unscrewing the 4 screws. 4  Remove the other carburetor cover and pull off the metering diapragm gasket. 5  Check the condition of all the diaphragm gaskets. Refit the primer bulb by inserting the 4 screws. 2  Check the primer bulb is not holed. 3  Turn the carburetor over and refit the gasket and diagraph. 4  Refit the end plate. 5  Hold back the throttle mechanism to allow this plate to be refitted. 6  Refit the HI and LO fuel adjusting screws.