my 450 is jumping out of fourth gear

5 replies to this topic
  • dirtman

Posted November 18, 2004 - 07:08 PM


Hi guys ,
I wonder if any one can help me?
I own a 03 450f with about 100 hours on it. it is well maintained.
when I shift up to fourth gear the bike starts to buck in and out of gear, but it only does this in fourth gear, it runs fine in first second and third.
I just replaced the clutch plates both fiber and the steel plates and the pressure plate springs, but this did not help. :cry:

  • ward63

Posted November 18, 2004 - 09:02 PM


I had the same problem. I when through everything, new chain/ sprocket, new clutch, oil filters and couldn’t find anything. The think that I couldn’t figure out was there were NO metal pieces anywhere in the filters. Anyway, I ended up splitting the cases and when I opened the engine up, there was little pieces of rubber everywhere inside. I'm not sure what these could be from, but they where everywhere. My only guess was one time a while back the valve cover gasket pushed in and that could have chipped away a little in there. Anyway, the inside of the engine looked very good other than the rubber pieces and the sprocket on the crankshaft was hooked like a regular rear sprocket gets. There were no missing teeth anywhere. Everything looks great. SO I’m looking to see what could make my bike slip in and out of 4th as well... I’m assuming that the rubber got in the gears or something and wouldn’t let it shift all the way into 4th. Any other suggestions would be appreciated.

  • GetSumBaby

Posted November 18, 2004 - 09:42 PM


I had the same problem - it just cost me $700 dollars to fix....

Good luck,

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • yzf450jack

Posted November 18, 2004 - 09:43 PM


You have a bent shift fork It rounded off the dogs on your 4th gear so it's not all the way in gear and it starts chipping away on the gear till it won't stay in gear at all :cry: need to split the case's and replace the two gears and the fork.

  • GetSumBaby

Posted November 19, 2004 - 06:29 AM


I had to replace 1 shift fork and 5 gears because fourth was jumping.


  • grayracer513

Posted November 19, 2004 - 10:07 AM


You have a worn 4th and 3rd gear pinion on the mainshaft (the third pinion locks fourth to the shaft when 4th is selected), and most probably a bent #1 shift fork. The fork either bent, causing the problem, or got bent trying to hold the 3rd pinion in enegagement under a load, which it was not intended to have to do. The gears are undercut so that they hold themselves together under loads, theforks just move them in and out of gear, and hold them in place during no load situations, like coasting with the clutch disengaged.

This is assuming it only does this in 4th.

Related Content


BIGBORE FOR YZ450F 2006? by Taattie94

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

James Stewart back on a YZ450F by YamaLink

Dirt Bike   Special Interest Forums   Pro Racing
  • Hot  47 replies

Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply

The "going back to the other darkside" adventure... by Monk

Dirt Bike   Make / Model Specific   KTM   250/350/450/505 SX-F & XC-F (4-Strokes)
  • Hot  113 replies

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.