If you have buddies that fly helicopters maybe one of them have a worn out/broken Hyper .50 engine? That carb (os 60L) is what I use on my own 91 FX and it cured all my problems (the very same as you describe) It is a truly fantastic carb and makes the engine dead reliable, but any carb with a 15mm throat will work. Get the Dremmel out and cut that needle off and I bet your engine will behave it self