RCpilet, this may be an obvious question, but have you opened up the reed valve restricter a bit? I remember back when I was playing with the old style Ryobi 31cc engines, bending the restricter tang out a bit made the single largest difference in RPM gain.

I still have a brand new twin-ring Ryobi 31 in the bones. Never got around to play with it, so it may respond differently.