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How much of an effect do new collets have on clearances?I have a few closers that are only slightly loose.
 

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1 to 2 thousanths of an inch. Over a period of time though they will revert to the same as the collets squish. The best way to gain consistent clearances is to make sure you keep the orientation of the old collets the same when you adjust the clearances with new shims. Once they so to speak get formed by impact wear they stay that way. Use a magnifying glass to determine the wear pattern.
 

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Is it preferable to just use new collets? On an older bike does it make it more likely that you'll need to change shims at the next valve check?
 

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Is it preferable to just use new collets? On an older bike does it make it more likely that you'll need to change shims at the next valve check?

No, and no. The likelyhood of changing shims is just what it is. If anything re-using old collets will cut down on the frequency of actual adjustments. A cross section of a used collet looks sort of like an S where a new one looks like an O. after a while new ones get that S like shape to them as well, increasing your clearances.
 

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The OEM half rings (collets) do work harden over time. That is they actually get stronger. But they do compress and deform slightly. I only change them when they are damaged (split in two or deformed grossly).

Another source of increase clearance is the OEM closer shim. It actually can "dish" over time where the half rings seat. I found this out when changing out a closer shim with a new shim. The new shim is not "dished". The closer measurement tool does not measure the extra "dishing". When I calculated the new shim size from the clearance I measured, then put in the new closing shim, the clearance was slightly too tight. The "dishing" allows the closer shim to ride up the valve stem slightly (maybe .001 or .002 inches). Next time you pull out a closer shim look at where the half ring sits and note how shiny the surface of the shim is.
Mike
 

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The OEM half rings (collets) do work harden over time. That is they actually get stronger. But they do compress and deform slightly. I only change them when they are damaged (split in two or deformed grossly).

Another source of increase clearance is the OEM closer shim. It actually can "dish" over time where the half rings seat. I found this out when changing out a closer shim with a new shim. The new shim is not "dished". The closer measurement tool does not measure the extra "dishing". When I calculated the new shim size from the clearance I measured, then put in the new closing shim, the clearance was slightly too tight. The "dishing" allows the closer shim to ride up the valve stem slightly (maybe .001 or .002 inches). Next time you pull out a closer shim look at where the half ring sits and note how shiny the surface of the shim is.
Mike
Thanks for the heads up! I had a suspicion about that once. One day I aspire to get zen with clearance changes.:)

P.S. Thanks for making "the kit". I like to tinker with my toys and having the shim set makes it enjoyable.
 
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