I bought a Magnum 91 for my Model Tech Dragon Lady and after brake in on
the ground ( 1 gallon of fuel) it seemed to run OK but when I took it to the field
for it's maiden couldn't get the darn thing to idle under 5200 RPM, way too high.
Had my original flight instructor test fly the plane for me and almost had a disaster
on it's first flight. Sent the engine back to Global and they replaced the cam, and
that took 2 1/2 months to get it back. Took for it's second flight, same things were
happening, wouldn't idle down and didn't have much power. Had our club resident 4-stroke
guru attempt to do some adjusting and even he couldn't get it any better, suggested it
be sent back again.

I broke the engine inusing 10% nitro with a combination of MAS 14-6 and Zinger 14-6
wood props.Finally sent it back to Global for second time and they said they would replace
the engine but opted for 90 2-stroke instead of the 4 stroke.

Just about everone at our field run either Saito (#1) or OS (#2) when it come to 4-stroke engines.