Had to do some minor repairs due to a stall of the engine on Sunday. My falt, was in too big of a hurry to fly and did'nt retune again. Getting bad about that. Got it back out today. Ok. First thing is the old pitts was not made for this engine. It was much smaller than this one from RCGF. After initial start up gave it about 1/4 throttle for a couple of min's to warm up, then comensed to tuning. And now it run's even better with the right size pipe. I think the other smaller pitts was boggin it down.