RE: ASP .21 Series 3
Ran it up for a few minutes today: 10% nitro, 22% oil (1/2 castor), OS A3 plug: 13,800 on old style MA 9x4, sometimes just going over 14; 15,000 on Bolly 8.5x4; won't try larger props till it's had a little more run time.
Contrary to first post, I did not find needle unusually sensitive; actually I thought it was perfect. Throttling was quite good even after very short run time: reliable idle below 3000, hesitated but didn't die when I snapped throttle wide open; adjusted low speed needle several times to improve transition and it became very good. It would not snap from idle to full instantly, but was just slightly slow...not what I would call a hesitation at all, but just as if you advanced the throttle quickly but didn't snap it. This may get even better as the engine is run in, but it's very good right now for anything except 3D (not that I do 3D anyway).
Muffler is very small...just an 1/8 inch longer cone than the muffler that came with the .12. Exhaust outlet is larger than on the .12. Otherwise they look identical.
Starting is instantaneous with a choked flip or two first. Great hand-starting; no starter needed. But I had to heat the head with my heat gun at first because the pinch at TDC was quite tight.
I love it!