The float level is a critical part of carburetor calibration. Changing the fuel level in the bowl will change the point that the main circuit starts to feed, alter the characteristics of an emulsion tube, and affect drivability and fuel consumption.
Float level, in mm, typically refers to the distance from the face of the carburetor top cover to the float. With the top cover held vertically (float pivot at the top) and the float tab (Lc) resting against, but not depressing the spring loaded ball in the needle valve, measure between the face of the carburetor top cover to the top or bottom of the float. On carburetor models where it is required to remove the float to replace the top cover gasket, the measurement should be made with the gasket in place to the gasket face.