airadical

I have an O.S. 52 surpass that I've had mounted upright on 2 different airplanes and had trouble with carb adjustment. Recently, trying to solve the problem I took the carb. apart and made sure it was clean. I have adjusted the valves using O.S. valve adjusting kit. The tank is about 10 ounce size using typical 2 line set-up and spray bar is very close to tank centerline. Using APC 12-6 prop max RPM is about 9400 RPM adjusted to 9100 RPM. The prop is balanced fairly well being just a little heavy on one side of the hub. The problem I've always had with this engine is idle mixture. I have to run it rich or it will die when I gas on it. At this setting the engine runs very rough and shakes the plane a lot. Also, when I invert the plane the engine slows down and smokes more like it's running rich. Today I changed the O.S. type f glow plug with a new one but it made no difference. These are very good reliable engines and all the ones I have seen idles and transitions to high speed smoothly. I have not had such good luck with mine. Any Suggestions?

Bax

My Feedback: (11)

You may have the high-speed needle too rich. Also, you can try lowering the tank a bit if you cannot lean the idle properly. Please remember that model engines have extremely-simple carburetors, and so fuel metering is not quite perfect. It's normal to get some roughness at idle. If the engine shakes "all over" when it's idling, we'd start to wonder at the strength of the airframe...that could also be a contributor. Many light weight airframes really aren't very good for supporting and engine and preventing fuel problems from the fuel being shaken-up inside the fuel tank.