I've got 3 of them... a pair of 40's on a Dual Ace and a 61 in a Harmon Rocket 3 - love them. Having said that when first two were new they both came close to being thrown across the field and into the plane-swallowing swamp, but by the third one I'd learned how to set them up and now won't waste money on any other brand of 2 stroke. (I only wish they'd start making 4 strokes - oh well.)

There's a couple of tricks with ST's...

- use low nitro fuels; 5% is heaps with them
- throw away the glow plug that they come with, it's rubbish. Replace it with an OS A3 plug.
- follow the break-in guidlines in the instruction, and when you think it's broken in it's still only 1/3 of the way there. These engines really get better with time.
- don't start twisting the fuel venturi round - you're only going to mask problems and create new ones
- make sure the carb's sealed well to the crankcase, there's no cracks or splits in the O ring round the carb's base, and that the pinch bolt's tight.

I flew my Harmon the other day for the first time in about a year. I'd stored it by squirting a bunch of auto transmission fluid into the carb & cylinder, but that was all I did. It fired up immediately, still transitioned perfectly, idled all day, and ran like a dream... just like both my 40's do. These are great engines, just misunderstood by the OS/Saito crowd who aren't prepared to put a few hours work into breaking them in and learning to tune them up. My only complaint with them is the big, ugly (but effective) mufflers and the dodgy muffler gasket - easily solved with an after-market muffler and leaving the gasket out, though I'm still using the standard mufflers (no gaskets) on my twin.