O.S. updated .25 SF has a remote needle attached to the backplate to keep fingers away from prop. Twin ball bearing-supported crankshaft. Schnuerle Porting (Schnuerle scavenging). Advanced bi-metallic liner process uses a double layer of plating material, rather than one thicker layer. This helps the metal to bond to the cylinder, and is more durable. Also, the plating process is more consistent, resulting in a more precise fit between piston and sleeve, for better compression, longer life. Side exhaust. One-piece crankcase. This product includes one expansion style muffler. One set of instructions, decal, and poster. One assembled .25 FX w/carb.

Long glow plug. Fuel with 18% (minimum) lubricant content and 5%-15% Nitromethane. All 5%-15% fuels we carry meet these requirements).