Whats up hipsters...

I have an os 61 fx thats about 5 years old.. it sat unused for a few years (no fuel in it, after run oil, and covered up to keep the dust out). I cleaned it the other day fired it up.. no problem.....did two flights everything perfect...On landing on my last flight, hit a rut in the field and cart wheeled it, broke the engine off the mount (glass filled mount)... New mount... inspected the engine and fired it up with no problems.

After my first flight this am I noticed it seemed under power so i landed it and noticed that I did not have much of any thing comming out of the muffler. I did have some oil backing up towards the fuel tank in the vent line. The engine powers up smooth and goes to idle without any problems.

If I lean it out, it runs fine... as soon as I start richen it up, the engine dies (nothing comming out of the muffler)....

any ideas???

thanks...

Are you sure that the engine in side and out is clean with no dirt in side of it? Also check the in side of your muffler
Mark Stogdill
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yep engine and muf are clean... some oil build up.. but nothing major... I am going to re clean them and fire them up here at the house...

....is there a baffle that may have come loose ?

No baffle loose that I can tell

Ok.. cleaned everything out again... no dirt of any kind... the muffler does have exhaust comming from it... I guess the main quistion I have is why is some of it backing up into my vent line that goes from my fuel tank? Is this just normal?

i doubt it has moved, but take the head of, and see if the piston sleeve is lined up.... you might wanna take the carb off, and take it apart carefully, and put it back on, and make sure it has a good O ring,


edit& also blow through it manually with a piece of fuel tubing and open close the carb, and needle valve and you should feel/hear difference

yep sleeve is good... carb is getting good air... I think my muffler is shot and its not building up back pressure...

If you cant see any external flaws on the muffler, then there probably is nothing wrong with the exhaust... are you Absolutely sure there are no pin holes in your lines..... pin holes cause lots of bubbles which can make a motor to run horribly..... sometimes they are hidden... i busted my a** trouble shooting a motor because and it turned out to be a punctured line.... If you motor is really running that bad, its worth pulling the external lines off and do the pinch suck and tongue method

Just a hunch...check your muffler vent. The same thing happened to me before with fuel backing up in the vent tube. A check of the whole muffler revealed everything was fine until I stuck a T-pin into the muffler vent and it was blocked with dirt! Once cleaned out, the engine ran great!