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Valve Clearance question

6 posts in this topic

Question for all of you-

When you are re-shimming valves what clearances are you aiming for?

Example- Tolerances are .20-.25mms. Current measured clearance is .18mm.

Are you going to reshim for .23ish mm to be in the middle range of the tolerances? .25mm to allow for the valve to tighten after more wear? Or anything in between? Does it matter?

I have my valves shimmed for the looser limits, but since then the bike has developed the famous valve "ticking" sound. Wondering if this is the cause and if I should reconsider my approach.

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The whole range, from tight to loose, is only .002", so it doesn't much matter, but technically, the ideal is the tight limit of the specified clearance. 

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Ok thanks for the reply. For what reason is it better to have them on the tighter side?

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Oh and one more thing. If you have a higher performance cam such as a Hot Cam, does it become more important to have them on the tighter side?

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Oh and one more thing. If you have a higher performance cam such as a Hot Cam, does it become more important to have them on the tighter side?

They will probably just tighten over time so I go right in middle of tight.

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The reason that the tight side is technically better (and why Yamaha uses shims in .01mm increments to achieve it) is that with less clearance, there is less impact between cam and lifter on opening, and, marginally, more net lift.

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