My sons 01 xr80 has no power at all it seems. Seriously I've read almost every post on here about them, but I'm having a few problems. I pulled the snorkel, opened the airbox, moved needle to 4th spot, can't do anything to the exhaust (end is welded shut) or do I cut it off, remove baffle, then re-weld? Seems like you have to have the bike wide open or it will just peter out on you up the slightest inclines. What can I do? Carb clean, did. Air Filter Clean, did. Plug check, did.