I tached my OS Surpass 52 running on GX-5 (5% nitro) fuel swinging a 12.25" by 3.75" prop at 11600rpm top end and 4400rpm idle. Do those numbers seem reasonable? I have tried to get a lower idle but the engine cuts out after about 10 seconds on a slower idle than that, which is no good for slow passes etc.
I'm sure it used to idle lower, but with the old props I used which were 11x6 if I remember correctly, but surely a bigger prop will increase the flywheel effect and allow a slower idle? [&:]

Cheers,