This is on an 09 yz450. My pilot jet was clogged up pretty good before this problem. It would run fine after it would finally start. Jumpstart to now, carb is clean with a new stock pilot. Starts great, revs great. After warming up and going for a ride, the bike will bog off idle, as far as I can remember, only when letting the clutch out and trying to get moving. It is like it needs reved up a good bit, but, clutch feels fine. It will rip hard on the top end once the revs finally get up there. I do not believe it to be a clutch problem. Any suggestions? It is kind of hard to explain unfortunately. I could probably get a vid if it is necessary. Stock pilot and 1 up on the main BTW.