how many guys do you know that have had to rebuild their 4-stroker? ESPECIALLY a non-race machine? I know of no one. To go along with that, Ive never seen anyone carb tune a 4 stroke, they are pretty much set and good to go right from the factory. They arent thrown off by climate change as easily as the 2 strokes. The 4 strokers are also just as light now, like i said, go to a MX track and take note of what guys are riding. Go talk to some of them and ask THEIR opinions, people who ride them everyday. Better yet, go to croom and talk to some, thats more of the riding your likely to be doing. Get people opinions who actually own and ride the 4 strokes all the time