Abstract: The method of locating and cutting an idle bypass hole in a carburetor body having a throttle section and a normally closed pivotal throttle plate therein on a longitudinal axis which comprises adjustably and guidably mounting a carrier upon a fixture base, locating and clamping a carburetor body upon the carrier and mounting a stationary contact finger upon the base. Further steps include advancing the carburetor body until the contact finger is in firm engagement with the throttle plate, thereafter clamping the carrier to the base and successively cutting the idle bypass hole through the carburetor body upon an axis at right angles to the body axis and at a predetermined distance to a fixed axis of reference. The cutting axis is arranged at a preset critical distance from the closed throttle plate. An apparatus therefor which includes a fixture base, a reciprocal carrier guidably mounted thereon supporting a carburetor body.