This RCV 60 sleeve valve cutaway engine was designed and built by RCV Engines, US. The cylinder liner rotates one time for every four strokes of the crankshaft. The port in the top portion of the liner is both an intake and exhaust port as it rotates through the combustion cycle. The liner is extended through a ball bearing in the front and is threaded for the propeller flange nut. Unlike most engines, the piston moves parallel to the propeller shaft.