Sounds like your numbers are just a
little shy of what Keith posted when he first introduced this engine.
Posted on 1/10/2006
We have also developed a gas version of the .51 Supertigre and the 2300. They dont run hot at 50:1 mix and I challenge you to wear one out. The .90 turns a 13x6 APC at 12,500 -12,800 rpm on gasoline and stock Supertigre muffler.
Keith
BME
Here's that thread:
http://www.rcuniverse.com/forum/m_37..._1/key_/tm.htm
Your 2000RPM shy of the posted RPM--maybe it just needs breaking in. I haven't seen too many engines gain 2000 RPM after break in. Actually, I've never seen ANY engine gain that many RPM after break in.