I have an OS 46 SF that I acquired from an estate sale (through a family in-law) so I don't have any history on the engine. I have flown the engine about 15-20 flights with no problems. Suddenly it developed a problem where it just quit running at full power. The engine seems to run fine below about 3/4 throttle but when it reaches full throttle then it just stops like a flame out, several dead sticks later we started trying adjustments on the ground!

I am a beginner but have had several "old pros" helping me (it has almost become a club project!). Thinking air leak, I've changed everything in the fuel system including tank and all new lines all the way to the needle. Nothing seems to work. There is plenty of fuel in the tank, no air bubbles in the line and I've tried rich and lean settings on both high speed needle and low speed adjustment, all to no avail.

To my knowledge the engine has not ever been disassembled and I'm trying to make sure I try everything prior to internal checks. Any ideas?

Thanks...
Bob
(second in command at YKnot Flying)