A throttle valve for a carburetor and a carburetor incorporating such a valve, the throttle valve comprising a disc, diametrically extending support shafts rigidly attached to the disc and dividing the disc into two halves, a semi-circular shell belt attached to one half of the disc adjacent the periphery of the disc and extending in a direction substantially normal to one surface of the disc and a plurality of teeth arranged in a semicircle adjacent the belt on the side of the belt remote from the periphery of the disc, the teeth being attached to and extending from said surface, curved in a plane parallel to said surface with the inside of the curve facing the center of the disc and being spaced by V-shaped notches.