YZ450F Slipping Transmission


3 replies to this topic
  • NianJay

Posted January 30, 2015 - 03:00 AM

#1

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. 



  • pomoco

Posted January 30, 2015 - 03:30 AM

#2

Its a pretty big job, but totally do able. You need a nice big clean workbench or two. Lay everything out in order. Take pics. Get a factory manual. I did my fifth gear, along with bearings and seals. Threw on a new top end. Put it all back in the bike and it started second kick! I finished at 11pm and woke up the next morning and left for a three day weekend riding trip.

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  • Mackprav

Posted February 11, 2015 - 02:15 PM

#3

I am having the same problem with my 2004 YZ450F.  I did split the case and the forks were bent and worn so I replaced them along with my baring, timing chain, and added a new piston.  When I took it out for a ride the fourth gear problem was still happening and I am still scratching my head about this.  When I go through the whups it seams to stall out and I am hoping it is a carburetor issue. I have dialed in my jets so really not sure what else to do.  Please Help!! 



  • Mackprav

Posted February 11, 2015 - 02:20 PM

#4

I am having the same problem with my 2004 YZ450F.  I did split the case and the forks were bent and worn so I replaced them along with my baring, timing chain, and added a new piston.  When I took it out for a ride the fourth gear problem was still happening and I am still scratching my head about this.  When I go through the whups it seams to stall out and I am hoping it is a carburetor issue. I have dialed in my jets so really not sure what else to do.  Please Help!! 

My clutch cable is stretched out and am going to replace it so hoping this might work!?







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