Valve Shim Sizes

4 replies to this topic
  • wRrooster

Posted September 19, 2005 - 09:31 PM


I've got some tight valves in my 04 WR450F that need re-shimming. I'm going to order up a few different sizes of shims to make sure that I have the right shims when I take my cams out for the first time. What I'm wondering is if all (04)WR450's come stock with roughly the same stock shim size? I'm assuming that both intake and exhaust come with approximately 175 (1.75 mm) shims?
Is it OK to assume that my stock shims are within .05mm of that size and order up the next few smaller sizes (1.70mm, 1.65mm)?
What shim sizes did you guys find in there when you adjusted them for the first time?
BTW- I've been reading this forum for a while, thanks for all the tips.

  • clark4131

Posted September 19, 2005 - 09:45 PM


This was in an '05, so take it for what it's worth, but I had 188 through 170. Now I know what you're gonna say, but Yamaha has their own factory shims that don't always go in increments of 5. It worked out good for me though, as I had a couple of borderline valves that were brought back to the low end of the range by swapping some of the odd-sized shims...SC

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  • tony1970

Posted September 19, 2005 - 09:47 PM


I ordered the Hot Cams kit from the TT store. It is a little pricey and you will get some shims you may never use, but it is a complete kit. I have not checked my valves on my 05 yet so wanted to make sure I had all the bases covered before I tore it apart. Did not want to run back and forth to the dealer 15 miles away. You can also by the packs of three through the TT store. Good luck. :banghead:

  • WildRide

Posted September 20, 2005 - 09:36 PM


The valves were so easy to do I buttoned my bike back up after recording the shim#/clearances and ordered the new ones online and went out riding (twice). Went back in a week or so later and checked my sons and did my bike in a little over an hour. The only thing I don't like about the job is the bearing retainer ring on sprocket side bearing cap, I always think it might fall into engine (a bad thing!). A good articulating pencil magnet makes bucket removal a breeze. My sons 250 requires a narrower feeler gage for the middle intake, if I remember correctly. IMHO the 250 is a better engine than the 426 in the respect of less vibration and ride-ability. He has bounced that poor engine off the rev limiter absolutely countless times with reckless abandon and I have yet to have to put a shim in, amazing, he just rides the P*ss out of it and it does not even seem to care! I just keep clean oil in it and it runs just like we got 2 years ago.

  • GCannon

Posted September 21, 2005 - 09:51 AM


Check those valve clearances. The Honda CRF 450 valve shims are the same diameter but Honda sells the shims in .025 mm thicknesses. This will give you a much finner adjustment . You can use the same chart instead of going from a 175 to a 180 you can get a 177.5 from Honda. Roughly .05mm is .002" and .025mm is .001" so you can get a one thousands difference shim instead of making the two thousands jump.

Make sure you are very careful not to overtorque the cam carrier caps. Also make sure the cam cap locating dowels are seated before you torque the cam caps.


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