O.S. FX series of high-performance engines have one-piece crankcases. Twin ball bearing-supported crankshaft. Schnuerle porting (AKA Schnuerle scavenging). Aluminum piston, steel cylinder liner and iron piston ring. Side exhaust with muffler with rotatable exhaust outlet. Carburetor with remote needle mounted on the backplate of the engine (to keep fingers away from the spinning propeller). Two-year warranty. This product includes one expansion style muffler (#E-4010) with screws. One assembled engine with carb. One package illustrated instructions, parts list, and O.S. decal. One O.S. #8 glow plug.

Fuel: 18% (minimum) conventional lubricant content and 5%-20% Nitro.