Thanks again for the replies, and keep them coming! I'm learning a lot about choosing the right engine; things like whether it's a "stroker" or a "buzzer". I like the sound of the 65 LA for ease of operation, short break-in, and cheap price. I like the price of the SK's, and have heard good things about them. I thought about the 91FX, but the price is almost in 4-stroke territory... I actually originally bought a Supertigre 90 for this plane, but it was one with the slot machined incorrectly in the carb. I couldn't get it to transition and got rid of it. (rich midrange) A couple months later I got a Supertigre .40 and it's been super right out of the box. I thought about getting another .90, thinking it was just a one-time lemon, but it seemed to vibrate a lot also. I have a good K&B .61 but don't think it would have quite enough oomph. Anyway, keep the ideas coming, I'm still trying to decide... Ross

p.s. I see the 91FX and the 90 SK are ringed. Would they idle/transition well after a few tanks on the bench?