CB Key FIX!!!!!

Well, it's been tree months since I've ridden and in that time I've had many feelings about ditching the 00/426 and getting anything red that doesn't have valves. My bike has been down since the new year. The problem? My CB key (thanks yamaha for the wonderful design) is gonna cost me about 500 bones. The bolt that holds the gears to the crank came loose and wreaked havoc. Right side case gone, right crank marred, many gaskets and seals destroyed and I now have a slightly lighter flywheel. The problem comes when the bolt is not tightened down properly which I think came after the third cb replacement on my bike. I should have replaced the lock washer. I believe it failed on me. The good side is that I get to replace the right side of my case with a 2001 unit which is splined. So, good-bye CB key problems! The moral of the story... If you continually have the CB problem, it may be cheaper to just update the crank (With my discount about $200+gaskets etc.). At least make sure you replace the lock-washer and crank down the bolt well when you do the work.

I hope my experience will save others.



Can you reliably replace just one side of the crankcase? I'm on my third set of crankcases and each time only the right side was damaged. Be careful, because once you install a seal or gasket, it may not be able to be reused. And as you know, gaskets and seals can get expensive.

Ya'll are making me worry about my 00 now. Is this cb key something I should be overly concerned about? I only have about 150 hrs on mine and have a 10oz flywheel wt. Is this a common defect on the 00? What symptoms should I look for? :)

I have a question. Did your balacer gear make a racket prior to the KEY failing? Or Did the KEY fail and the engine stop?

I am in the process of replacing by second cb key. I suggest that everyone inspect there's. My cb key was so worn that it actually cracked the balancer drive gear in which it goes into.

If your bike isn't making some serious noise on the right side of the case you might be all right. I could definately tell that there was something wrong with my bike. (2000 426) I have bought another cb key but am first going to try to make my own. A little larger with a tighter fit. However, I believe the real problem is that the nut that holds the gear down keeps coming loose, as some of you know. Good Luck, I hope this doesn't happen to you.

Fox, I have a friend who has had none of the CB key problems on his 00. You'll know when there is a problem. It sounds like a bearing is out, or the timing chain is slapping. I don't think I'd worry about it if you don't have any of these symptoms, but any new and odd sound should be investigated. Scott does have a point though, It may be a good idea to look things over.

Shawn, The previous three times the bike made the racket that was described above, but this last time, there was no noise, just a lot of friction as the nut ground itself into any surrounding aluminum. The key didn't fail, but it was about to. On only five rides, there was an amazing amount of play already.

My question is has anyone replaced the 1/2 crank and gear on their 00?


By the way, I re-read my original post. That flywheel thing should say I have a lighter clutch basket. The flywheel is fine. Sorry if I freaked anyone out.


I've replaced my second CB key, but I had a tough time getting enough torque on the nut. I'm looking around for air compressor/tools (in case I need to fix it again).

Rich, I hope you can reliably replace the right side of the crank. I'll have to do some research before I complete the work. Thanks for the heads-up, I'll keep you up on what I find out.


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