Rotary throttle valve carburetor with valve bore air flow

A rotary throttle valve carburetor, comprising:

• a main body having a main bore through which a fuel and air mixture is discharged, and a valve bore that intersects the main bore and has a bottom wall;
• a throttle valve plate coupled to the main body and having an opening aligned with the valve bore;
• a throttle valve received within the valve bore for rotation and axial movement between an idle position and a wide-open position, and wherein the throttle valve is closer to the bottom wall in the idle position than in the wide-open position, and the throttle valve extends into the opening in the throttle valve;
• a first chamber defined in the valve bore between the bottom wall and the throttle valve;
• a second chamber defined in the valve bore between the throttle valve and the throttle valve plate;
• and
• at least one passage communicating with either the first chamber or the second chamber to permit fluid flow into or out of the first chamber or the second chamber, wherein the at least one passage is open when the throttle valve is in any position between and including the idle position and wide-open position.