Abstract: A substantially annular flow enhancing insert is positioned in the carburetor side of the roof prism shaped reed valve inlet frame of a two-cycle internal combustion engine. The insert's flow passage is shaped so as to prevent flow separation due to large angular changes in the flow passage. The insert has two extended tapering wedges, each wedge positioned flush against the inner surface of the two opposite parallel triangular walls of the inlet frame. Each wedge directs the inlet flow smoothly to the reed valve openings and eliminates flow passage discontinuities that are normally present within the inlet frame. The remainder of the insert is closely matched to the carburetor duct and reed valve inlet frame contours so as to eliminate surface discontinuities and thereby enhance the flow into the engine.