03 yz450f gearbox woes

3 replies to this topic
  • Mperry48111

Posted December 30, 2008 - 08:10 AM


I have a 2003 yz450F. While riding, it will periodically shift itself into first gear. I don't know if this is a clutch issue or a gearbox issue. Any ideas would be greatly appreciated.

  • grayracer513

Posted December 30, 2008 - 08:48 AM


Sounds like a big shoe issue.

Please provide a more elaborate description of when/how this occurs.

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  • Mperry48111

Posted December 30, 2008 - 09:06 AM


There is no real rhyme or reason to when it happens. That is, it is no more likely to happen when hot than cold. I do have difficulty starting the bike while in gear - it lurches forward when I attempt to kickstart it. I know this suggests clutch issues. I am just hoping I don't have gearbox issues as well.

  • grayracer513

Posted December 30, 2008 - 11:39 AM


You're not helping.

Does it happen when you're riding? At a standstill? On hard landings? What?

The only way that the trans can change gears is for the shift cam to rotate. A heavy shift lever, a weak or broken centering spring, index lever or spring, or hitting the lever with your foot are just about it.

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