OK, when my helicopter is at a certain RPM (not sure how fast) it makes a really smooth humming resonace but doesn't have too much power. When I raise the head speed I belive it is going on the pipe because it gets much more power but the engine gets rougher and makes the tail do a random, very fast micro wag. The transition from the smooth resonating hum to what I think is being on the pipe is VERY rough. The tail makes it look like I'm getting hit by radio interfearence it gets so rough and random, once it clears that the helicopter flies fine but still micro wags.

Any idea on how to fix this and what is causing it. I REALLY like the sound of the humming resonance and wish it made that sound when it was on the pipe. I'd even lower my headspeed to get it to do that while in normal mode!! It makes a sort of waaaAAAAAAOOOOooooM sound every 1 to 2 seconds. Sounds like the engine is running perfect when it happens, its just a little low on power and I'm afraid that the blades might over speed a little which will put me into the rough point at a bad moment.

Over heating , I had the same problem than i installed a governor and that stopped over speeding. Plus your not on the pipe is it's running rough, what is the gap size?

Gap is aprox 1/8 inch nd I know for sure it's not overheating, it is running cool. The spit test reveals a VERY slow boil off.

After adjusting the head speed down and readjusting the mixture I found that I am now getting that overspeed problem in between hover and full climbout. I can't wait for my 9Z, 13 throttle curves will be VERY helpful to me. My idle is lean but fine, my midend is rich but fine, my 3/4 throttle is lean and my top end is fine. Fuel pumps and tuned pipes do funny things to OS engines, but I sure love 'em!


OK, now at what head speed does the wierd rappy oscolation start? Is it 1400? If so I'm guessing That at 1500 my engine runs really smooth and at 1700 it starts to act funny and at 1900 it runs a little rough. Have in mind these are all guesses since I do not have a tach.