I am looking for some help on setting the needle valves on a ys 91 st engine that i put in my helicopter. I have become frustrated with it and it is probably because i have never delt with the 3 settings for the needle valves. The only setting that seems to be right is the idle at about 2.5 and that is out of the range called out on the manual. The hover and high throttle needle valve settings i do not even think i can get close. I have spent hours trying to figure this out and have had no luck even with reading the forums. It seems like the helicopter has no power after 1/4 to 1/3 throttle. Sunday I spent another day trying to get it running and went through about 6 more number 8 glow plugs and the bolts that hold the head on the motor actuall fell out which i have never had heppen before. I am looking for help because I have been messing with the motor for the whole season and would like to get it straightened out.