Hello Bax,
I have an older OS .50 FSR I bought new and put 1-1/2 seasons on. Great engine. I misjudged power lines and flew into one. Plane divided and pancaked to the ground. Runs OK on new plane but if I do high alpha, it breaks into a raspy ring-ding sound that I can't figure out. Sounds like a dirtbike winding down after reving. Quits from there. Compression weak when warm. Was in a cowl. Overheat? Bad ring? I like this engine and would like to find parts.
Thanks, Dan