Yeah, I can't quite say I agree that 4-strokes are smoother. I put a .26 surpass on a little plane that I had found in a dumpster once. It ran great but had a little more vibration that my .25 2 stroke that I also ran in that plane for a while. I had a Saito 1.50 in a GP super skybolt for a while. The performance was obscene, but so was the vibration. I'm amazed that plane never came apart with that thing in it. Even with the props balanced to within a gnats hair, all my 4-strokes tended to vibrate a little more than my 2-strokes. I theorize it's the power strokes occuring at half the frequency that does it.

As for noise, 2-strokes have gotten a bad rap, I think, because of the exhausts used on them. Especially gassers, with those little can mufflers on them. May as well run them with open exhaust. But with a good exhaust, they're nice and quiet. My big gasser with the intake and exhaust silencers installed is super quiet even inside the airplane - the prop is about the only thing you can hear with maybe a little whine audible at full throttle.

My all time favorite glow is the OS 1.40 RX which, with the $$$$$ OS pipe is barely audible above the prop noise. It was almost like an electric, well not quite, but very quiet.

I still prefer 2-strokes myself, even for full scale, due to the lower parts count. And, in the 40 to 50hp range, which is where I tend to be, there are no economically viable competitors to the 2-stroke motors as of yet.

In R/C, that's changing since the 4-strokes are getting really good. I still prefer the 2-strokes though again for the lower parts count and a little lower cost. I'm jonesin' for another 1.40 RX and a pattern plane already. Who knows when I'll give in....

LS