This is the O.S. New $309.99 (31% off). FS56-a Four Stroke Engine. Same mounting dimensions as the FS-52 Surpass.:. Features: * Improvements over the original FS series include Elimination of Crankcase venting-excess crankcase oil is now draw into the Rocker Cover, injected back into the combustion chamber Stronger Connecting Rod, Wristpin and Valve assembl Extended intake tube on Carburetor restrains the reverse flow o the air/fuel mixtur Decreased width Camshaft housing for less interference with side of aircraft nose section.:. * F-4040 muffler with adjustable offset and outlet direction fo easier cowl installations.:. * 40NA two needle Carburetor.:.