Minnflyer, You mentioned in two of your post that 4 strokes are cleaner.
4-Strokes run MUCH cleaner too! They generally leave about one tenth the oily residue on you plane than a 2-stroke does. I use 4-strokes almost exclusively except in my real "hotrod" airplanes. I'm always amazed at the mess after flying one of my 2-strokes!
That's totally the opposite on my end, I find that the 4 strokes make more then double the mess on my planes then my two strokes do.
Now maybe its just the smaller four strokes that are cleaner or maybe its the brand of 4 stroke, who knows as I run 100's and up. I have three, 2 strokes and two four strokes and the 4's leave by far more of a glob of waste on my plane then my two strokes do. Maybe its because they have to run richer then the two strokes *shrugs* I have one Saito 100 and one OS 120 FS that has yet to be fired up. All I can tell you is my Saito 100 leaves a pile of gue on the bottom of my Edge.
Randy