Here's my son's 20 dollar eBay ST 51. Runs like a top on 20% oil, 15% nitro, 11x6 APC, OS8 plug. (Spinner and prop in first picture were soon replaced with a Dave Brown and APC well balanced, big difference.) It had loose head screws at first, but after that I had no trouble with it. New carb fresh o-ring from one of my Stunt engines, didn't mess with it after one session setting the mid range, then a super accelerator, great idler, and almost as sweet as a 150 dollar OS 46 AX or 200 dollar 55 AX.
I have two ST 51's in Stunt models and run them on 22% oil, castor/synthetic mix. First flip, steady as a stone.
Chris...
Last edited by stuntflyr; 01-08-2015 at 12:45 PM.