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Valve Shim Suggestion

Old 07-16-2012, 12:14 AM
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Valve Shim Suggestion

Hello all,
My bike has almost 20k and broke into her for a valve inspect/adjust. All were perfect except the rear intake was a bit tight. I say a bit as the .006 had to be forced while all the others were perfect (it would slid through with a little friction but the next size would not). While this was still in spec I decided to try some smaller shims.

With the new ones installed it is now a bit loose on this intake valve. I can even get a .007 to slide through. Now this is still in spec but I think I should go back to what was originally in there. This may be a bit of a stretch but since (from browsing here) that the front tends to be rich that by having the rears on the tighter side of tolerance that it may get a tad more air and be the best way to go rather than having them on the loose side of specs. Anyone have a recommendation or confirmation on this?

Thanks in advance - And, thanks for all the contributors, I have learned a ton doing a recent, significant (for me) tune up to the bike.
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Old 07-16-2012, 12:33 AM
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What shim size did you take out and what did you replace it with? Also di you actually measure the shim you removed or just take the number off of it?

Were you using one of the kits, like the Hot Cams for the replacement shim or did you order the shim you needed?

Just asking as most "kits" only have .05mm increments where the factory also has .025mm increments.
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Old 07-16-2012, 08:10 AM
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Originally Posted by 8541Hawk View Post
What shim size did you take out and what did you replace it with? Also di you actually measure the shim you removed or just take the number off of it?

Were you using one of the kits, like the Hot Cams for the replacement shim or did you order the shim you needed?

Just asking as most "kits" only have .05mm increments where the factory also has .025mm increments.
Of course I can't find my paper written down so will have to take them out to know again for sure (and possible re-measure) but I believe that one was a 202(#1), the other is still out and is a 205(#2). I put the 202 in the other side (#1) as yes, from the measurement, this is what it called for.

You are correct I got the .195 which was slightly under what I actually needed for #1 but here's the thing, the 202 (#2) is correct (as swapped) and it still will fit the .007 gauge through it.

Perhaps the measuring wasn't as good as required - used a buddies micrometer and measured several times after re-zeroing and basically taking the measurement that came up most. Thanks Hawk.

Also, I don't think there is a shim between the .202 (actually a .2025 right?) and a 205?

Last edited by strokeburger; 07-16-2012 at 08:13 AM. Reason: missed
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Old 07-16-2012, 10:02 AM
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Measuring the clearance does take a bit of practice to get the "feel" for it.

Also running toward the loose side of the tolerance will not hurt anything, in fact some people do it on purpose. As the clearances tend to tighten up with use on OHC engines.

If they open up, then you usually have a cam or bucket wear issue and that needs to be tracked down right away.

So setting them to the loose end will give you a longer interval before they need to be adjusted again.

There is no shim between the two you listed but remember they are in mm so the number isn't .202 or .205 but actually 2.025 and 2.05 which works out to .001" difference between the two sizes to us 'mericans

For the front cylinder going rich in the mid-range read my carb set up thread. It is much easier to do and more controllable than messing with the valve clearances.
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Old 07-16-2012, 11:53 AM
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Thanks again Hawk, I have read your carb thread a couple of times. I bought new in 02' (yes haven't been riding much lately) and shortly after put of the big 2 brothers full system, k & n and (I believe) dynojet kit. After reading your thread as well as other comments it sounds like I should do something else. Too bad I can't find my stock stuff anymore! Again, thanks. I'm gonna bolt it back up on the loose end and run it
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