If you're looking for a plane to fly your 91 FX with, then I think you'll be much happier with a significantly lighter plane. When a manufacturer says eight pounds or whatever the gram weight was, it's likely you're looking at 9 to 10 pounds realistic all up weight. I have flown a 15 pound pig of a Telemaster on a 90 size two-stroke. It flew OK for a trainer, but not like an Extra should fly. ARF manufacturers are notorious for understating their products weights, and specifying nominal engine size that will get the model off the ground, but not fly with grace and style and the all-important reserve power.

I have flown with great satisfaction a 6.5 pound Kangke Cap 232 Sport on a Magnum 91 two-stroke, which was very comparable power-wise to the OS 91 FX. That was a good combination, with good vertical authority and very steady slow flight behavior.

I am getting ready to put together a Superkraft Extra, which is pretty close in size and weight to the plane you are looking at. I'm thinking SuperTigre 2300 (1.4 cu in) for power. The Moki 1.35 would also do well. A 1.20 two-cycle is the lower limit of what I'd want for power.

But if I read you right, you're saying you have the 91 FX, and you're looking for a plane for it. My recommendation would be something with a weight specification not more than seven pounds, preferably close to six pounds, or 2800-3000 grams. I have a Kyosho Cap 232 Sport that is waiting for a new cowl, in which I've mounted an MVVS .77. Your 91 FX would fly that plane like gangbusters. This plane is marketed as .46 two-stroke size.

The only way I would put a 91 two-stroke in a nine pound plane would be for general sport flying and mild aerobatics. If you can be happy with that, then maybe the combination you're looking at would be OK.