Steve Roberts

Bill,

I recently obtained an old but slightly used FS 61, my first 4 stroke. My question regards the exhaust pipe. It has a smooth end with no way to attach a muffler. The engine runs well but when pointed straight up it seems to loose a couple thousand RPMs. My thought is that this is normal and due to the lack of pressure in the fuel tank. I know that parts are no longer available for this engine but was wondering if any of the current OS four stroke exhaust header and muffler assemblies would fit the FS 61? Failing that, I have located a source for the correct exhaust header for the FS 61 which will accept a muffler; however, it doesn't include the muffler. Do you know if any of the current 4 stroke mufflers would fit that header?

Or should I just fly the engine as it is and not worry about it?

Is there a target RPM range that I should prop the engine for?

Thanks

Steve

Bax

My Feedback: (11)

At this time, we'd not have any parts specific to the O.S. FS061, and neither would O.S. The engine will run perfectly well without a muffler or muffler pressure to the tank. The pressure to the tank does alleviate some leaning when nose up or when the tank gets low, but doesn't completely eliminate it. Exhaust headers for the current-series of Surpass engines don't fit the older-series engines. If the noise isn't bad enough for your local flying field, then the engine will run nicely with or without one.