Adkins Corsair T80 100cc Rotary valve 51.1 piston. Piston is tight. Seems to be in good shape does have a broken fin as you can see in the picture on the cylinder head. Complete ignition, carburetor, and header Highly recommended taking it apart and going through it. As it been sitting for years. Was used in the late 80s early 90s. Running WKA manufactured cup a top-five engine back in the day.