RE: worst engine ever
OS 71 Ultimate (blue top). Mine was horrible and would not run steady. Yes, the needle valve stayed put, but the engine would run fine then start to fatten up all on its own till it stopped. Lots of guys on RCU with the older one like mine (perhaps two years old or so) had the same problem. I could never get it right. I gave up and sold it to a guy that said he could make it run. Supposedly later ones of the same engine were good, and I read about how much they are liked.