yzf 450 07 lost faith!!!

5 replies to this topic
  • ryzman

Posted October 22, 2009 - 11:43 AM


Right hi thumper talk!

my 07 450 is slightly tuned running 57.3bhp and has been fine all year racing mx.. until it busted the out put shaft.. second gear was also worn (or damaged-hardening had started coming off) replaced these parts and all bearings in case!!!

bike was then better than before..... until

last weekend, last race of the season.. the gear opposit second gear (think its called second gear idler??) broke and destroyed second gear:banghead:

now i have lost all faith in the gear box... although all the other gears look good no damage appart from 1 small chip about 1mm but probably smaller

i love my yam and really cant afford to get a new bike but also cant afford to replace every part in box as this totals to around £800

any sudgestions on how durable these boxes are and have i just had bad luck?? thanks!!

  • NortonMoto

Posted October 22, 2009 - 01:00 PM


Part it out and buy another, Use ebay

  • ryzman

Posted October 22, 2009 - 01:34 PM


really!!! i still gotta fix this one though.. and cant bodge it as someone will have it break on them and it could happen at a really wrong time on track... also if i dont repair it properly it would give me bad mx karma.. and its worth jack shit broken

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  • grayracer513

Posted October 22, 2009 - 01:39 PM


There are two gears in each pair (don't think about that too much), the pinion, which is on the main shaft, and the wheel, on the output shaft. In ANY situation where either gear in a pair must be replaced due to a failure or degradation of a load bearing surface, the gear that mates with that failed surface should be replaced also, and if you failed to do so, the second failure was as much your fault as anyone's.

YZF gear boxes have no particular rep for being either weak or unusually sturdy, but they don't fail very often, either. IMO, transmission failure are more often the rider's fault than not.

  • ryzman

Posted October 22, 2009 - 01:56 PM


:bonk: after i had repaired last time i knew in the back of my head i should of replaced the pair of gears... but.... i didn't.... so in theory if i do it properly and spend wat needs to be spent it should hold up... i'm going to have the other gears crack checked and then go from there...:bonk:

  • Polar_Bus

Posted October 24, 2009 - 04:13 AM


any sudgestions on how durable these boxes are and have i just had bad luck?? thanks!!

Extremly durable, if not "bullit-proof".

Until reading this whole thread, I was going to pull apart my tranny for no reason in fear of blowing gears out the side of the case. :bonk:

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