I bought my husband the Saito FA170R3 and he put it in the small Yellow Aircraft Sukhoi. It has about the same size and weight specs as your Corsair. They recommend a 1.20 to 1.80 4c. This engine flew the plane, but my husband eventually took it out and put in an OS 1.60 2 stroke that he was much happier with. Also, if you are new to 4 strokes, the radial will give you nightmares. There are several threads on here about them, I believe. They are great when broke in, but they have an extended break in period and are very picky. It will require a great deal of time and patience to get it running just right. Plus you will probably require the added weight of an on-board glow driver. We ran ours without one, but we had to hand fabricate our system to start the motor. I believe these engines are better suited to an old bi-plane with a big round cowl. The .90 will definitely not fly this airplane. The 170 will, but depending on how you want it to fly, you may or may not be disappointed. I would recommend the Saito 150 at least and would probably opt for the Saito 180 myself.

Carol Cox
Gulf Coast Gulls