Bike: 2004 YZ450F Problem: 4th gear slips in & out (jerk motion under acceleration in 4th). My transmission slips when I'm on the throttle in 4th gear and only 4th gear. It feels as if I'm constantly fingering the clutch. It grabs then miss grab then miss. I can ride in 4th gear as long as I take it easy but as soon as I start to open the throttle it starts again and doesn't stop until you're back putting around (taking it easy) in 4th. I've read that it could be the dog gears rounding over and becoming dull or it can be bent shift forks? I thought bent shift forks wouldn't allow me to engage into 4th gear rather than 4th gear slipping??? Either way the cases have to be split. How hard is this job? Would I get finically raped if I were to take it to a shop & hand them the motor for the tranny to be fixed? I mean I rebuild a 2stroke top end with out a manual just YouTube videos so I'd say I'm somewhat mechanically inclined. I just don't feel like getting into the internals, but I'd try it if its not TOO hard.