Dougwill...

Don't know why yours won't run. Mine have always run exceptional with the 30% Nitro. My best guess is the older engine design did not allow it. I know Magnum engines don't seem to benefit much from the higher Nitro. I did some thrust tests on a Magnum engine and couldn't hardly notice any differnce in performance while the Saitos and YS inprove significantly.

My guess if you use the 30% in the 100 or 125 you won't have a bit of problem. I have both those engines and mine run fine and are easy to tune with the 30%. I use Cool Power Heli fuel.

Good luck.

Thanks
Barry