FIG. 1 is a perspective view of a carburetor float bowl showing my new design. FIG. 2 is a front elevation view thereof. FIG. 3 is a right side elevation view thereof. FIG. 4 is a left side elevation view thereof. FIG. 5 is a rear elevation view thereof. FIG. 6 is a bottom view thereof; and, FIG. 7 is a top view thereof. The broken lines shown throughout the drawing are for illustrative purposes only and form no part of the claimed design.