A carburetor with throttle shaft retainer system. The throttle shaft retainer system employs a retainer member in the form of a retainer pin or retainer clip that is pressed into the body of the carburetor to engage a retainer groove formed about or partially about the circumference of the throttle shaft. The interaction between the retainer member and the retainer groove prevents movement in the axial direction of the throttle shaft. With certain drilling and machined cuts to the throttle shaft, the retaining pin acts as the wide-open-throttle (WOT) stop when the throttle is rotated to a WOT position.

A carburetor for a two-stroke internal combustion engine whereby airtightness is maintained and intake of uncombusted fuel into an air path is prevented. The carburetor includes a circular cylindrical valve hole and a rotary valve fitted into the valve hole such that it can rotate and is disposed perpendicularly across a fuel intake path and an air intake path which are formed substantially parallel with respect to each other, and a fuel supply-side bore which controls the flow rate along the fuel intake path and the air supply-side bore which controls the air capacity along the air path pass through part of the cylindrical portion perpendicularly to the axial direction of the rotary valve, and annular recesses formed in part of a circumferential wall of an outer circumference of the rotary valve so as not to correspond to at least the fuel supply-side bore and the air supply-side bore.