I have a 60 size PT-19 ,with a saito .80 in it. flys great. I only own saito 4 cycles and have never had a problem with any of them. I take that back I have a OS 1.6 four stroke that I have not run yet. The only thing I have had to do with my saitos is adj. the valve clearence during break in and once after break in. I am sure there are many good 4 strokes out there . I'm just a saito kind of guy.........