Maybe someone has direct experience with this but I'm guessing the Saito .91 should work fine depending on what you're after. Various 61 size 2-stokes have been reported to need at least several ounces of nose-weight to balance, and typically outweigh the Saito .91 by several ounces to begin with. Glowplug (read above) dropped a GMS .76 in his and didn't need any additional nose-weight -and probably has a full 1 hp more than the .91 to play with. Seems he should get the sensible choice award hands down in my book. -I got hard headed, reversed my decision to buy a large 2-stroke and will be using my Saito 72 just to see if I can get away with it, and get certain dubious bragging rights. Also, I hate breaking in new engines. I'd rather spend the time it takes to properly break in a ringed engine like the GMS entertaining myself by re-doing the tail group, using pull-pull controls etc. to keep the overall weight down and to avoid adding nose-weight. -There go the ARF advantages right down the tubes. what the heck.