How many times have you replaced the cb key?

12 replies to this topic
  • 4banger

Posted October 30, 2001 - 07:39 AM


I am on my 2nd time. I again heard the noise only after about 4 rides since I replaced the key with a yamaha part. I got her all powerwashed up and ready to tear down for the new key. My question is: How many hours is average for the key to last? It seems that my last key only held out for about 8 hours. It is a pain in the ass if I have to do this every 8 or so hours. What is your experience with this? My bike is a 98 yz400.

  • Scott_F

Posted October 30, 2001 - 10:28 PM


Do a search on my posts. I recommend making a key that is longer and tighter than the oem part.

  • Glen_T

Posted October 30, 2001 - 10:51 PM


I've had to replace mine twice. After the first cb key went bad, I bought about three stock keys and some 5mm key stock frome Scott F. I put Scott's key in first and got about a year of use. The second time, 3 rides ago, I put in a yamaha key just to see if it would last as long. I doubt it because it is shorter and less tight than Scott's key stock. I'm guessing that each replaced key will last just a bit shorter than the the last.


  • scottzx7rr

Posted October 30, 2001 - 04:34 PM


Mark and I were talking about it this weekend at the VSTA ride about using the Longer and Larger Key Stock.

Just out of curiousity why does this only seem to affect the '98 the most?

  • 4banger

Posted October 30, 2001 - 09:53 PM


Thanks for the replys. I ordered 3 keys but don't want to do this every 4-5 rides. Where should I get the key stock from and how do I tell what the hardness or quality is?

  • xrracer36

Posted October 31, 2001 - 04:25 AM


what key? what does it do? please fill me in. i am currently in the process of waiting for a front cam chain guide to come in (about 1/4 inch broke off the bottom of mine. ???)
anyone else had this problem?

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  • Glen_T

Posted October 31, 2001 - 01:19 PM


I thought the problem occured most often on the 00/426 or any big bore 400. You need to get 5mm keystock. I think Scott F got his from McMaster Carr. If you have a 2001 or newer you don't have to worry about the problem as they have gone to a splined crank.


  • scottzx7rr

Posted October 31, 2001 - 07:27 PM


The local Hardware store(True Value) has it in stock here in KC. They have it in 24 inch sticks for that size. Might try them.

  • BK14MX

Posted November 01, 2001 - 03:04 AM


I have an 00' 426, what is the problem you are speaking about. I don't want to find out after my engine explodes or anything!!

  • 4banger

Posted November 01, 2001 - 11:33 AM


It's not an exploding engine thing. When and if you hear a slight knocking sound, then you probably have to replace the key. As long as you don't let it go too long, everything is fixed for about 2 bucks. It is just a pain in the butt to replace the key. I was looking at the McMaster-Carr online bar stock listings and saw 18-8 stainless steel and high-carbon plain steel. I think the high carbon would be better, but it doesn't seem to be available in metric. Any insight on this? Also, oversize or undersize?

  • BK14MX

Posted November 02, 2001 - 05:48 AM


thanks for the info. But I don't have any idea what it does. Wheres the knock come from??

  • Glen_T

Posted November 02, 2001 - 06:47 AM


The knock comes from the key wearing out on the CB-Gear. It forms a bit of play and then the sound is a bit like a loose timing chain or blown bearing in the bottom end. Both of my keys lasted about a year (stock and the replacement. I am on my third key now.) The sound was very pronounced on my machine (00/426). My friend's 00 has not developed the problem. ??? I guess some do and some don't. If you search CB-KEY, you'll find lots of info about this.

  • BK14MX

Posted November 02, 2001 - 10:05 PM


thankyou glen, Mine hasnt so far, Knock on wood!

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