ORIGINAL: jeffk464
I was thinking of using a super tiger 91 or SK 90, but not sure if these motors are totally reliable or not. Also it looks like the 75AX almost matches them for power and by their recommendations you can run bigger props.
Depends on what you want and what kind of runway you fly from.
If you look at the GP specs it says ".61-.91 2-stroke engine". A .61 will get it airborne (see caveat below) but won't fly it with anywhere near the edges of the flight envelope of this airplane. Put simply, it ain't as fun!
This is a very capable airplane and deserves an engine to match. Yes, a .75 will be a little better, and a .91 better than that, and the 1.20 4-stroke (which is what I have) significantly better and the YS 1.10 probably the ideal engine for this model, and a 1.20 2-stroke slightly overpowered (if there is such a thing
). Where you settle on the spectrum is up to you. But just ask yourself, when is the last time that the RPM figures you got matched those claimed by the manufacturer?
Caveat: And if you fly off grass... depending on the condition of the grass you may need wheelbarrow tires to get up enough speed to lift off.