Will the OS FS70 Surpass 2 work without the muffler and with just the pipe?


Thanks!

Any of the O.S. Max four-stroke engines will run well without the muffler. You'll just get more noise.

You lose the extra help the muffler pressure gives to fuel pressure, but just open the high -speed needle a bit. Make sure the centerline of the fuel tank is centered on the needle valve and the tank's as close to the engine as possible (you want the fuel lines as short as possible).

Thanks!

How do you prime the engine without the muffler?

You can prime the engine by opening the throttle to full, choking the carb with a finger, and turning the engine over until fuel starts to spit out the exhaust. Remove he finger, close the throttle to just above idle, turn the prop over slowly to make sure there's no hydraulic lock, apply the glow plug battery, and start the engine.

Ok, we took the muffler off and drilled a hole in the tube and put the nipple on it. So the pressure line is still going to the tube.

However, I now have a problem where the engine tries to die at full throttle. Now, the engine is pretty new. I've only put about 7 or 8 tanks through it. I noticed someone had a similar problem with a Saito engine.

Should I bench run the engine with the glow plug ignitor on?

Thanks!

Michael

Your engine's idle mixture is most likely too lean. Richen it a LOT, start at part throttle and then work on the high-speed setting. Run at full throttle, very rich, for breakin. Gradually lean the high-speed needle. Once the engine will sustain running at peak RPM, you can retard the throttle and work on the idle mixture.

Thanks for your help!

However, we discovered that the nipple in the valve was inside the tube too much. So it was pulling air OUT of the tank instead of IN the tank.

Works fine now. Thanks anyway!

Michael