I have trouble running my YS 91 AC 4-stroke engine in my XL-PRO II in the high RPM area. In the low and middle RPM area it seems to be okay, the engine develops at nice massive smoke, evidence of good lubrcation and cooling, but in the high RPM area the smoke dissapear after a little while in hover, and the RPM drops slowly. The manual tells the highspeed needle-valve to be open 1 1/4 - 1½ from fully closed, my needle-valve is now 5 3/4 from fully closed, it helps a little bit, but the problem is not eliminated??
When I put on my canopy/hood, the engine turns warm in a few sec.
I run Cool Power 30 % nitro, and I think the oil-mix is 23 %
How fast should the engine run in hover?