Valve shim selection

woodybelle

woodybelle

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Joined
May 10, 2006
Messages
541
Age
72
Location
Sonora, California
Bike
2006 ST1300
I just finished replacing 4 shims on my ST1300. I had 2 intakes at .004" and 2 at .005". I wanted all these to end up at .006". The shims are available from Honda in .025mm increments which is very, very close to .001" increments. So to get .002" more clearance you just need to get shims 2 sizes thinner than the ones installed. To get .001" more clearance just go down 1 shim size. I see no need to use the formula, which seems to cause confusion when conversions are done from metric to standard. There is a list of all available shim sizes and their part numbers in STWiki which will help you select the proper shims. I hope this helps make a simple matter simple. Just remember that Honda rounds the sizes up and down so a 198 shim is actually 1.975 etc.
 
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I've done a few shim changes on 1300's and don't understand why some people prefer conversions from metric to standard to metric.

I stay metric and don't like to use the Service Manual formula. My process for calculating the new shim is simple. Since the shim goes under the valve bucket, if you need more clearance go with a smaller shim. If you need less clearance go with a larger shim. HotCams shims go in ranges of .05mm. So I measure the old shim and either add or subtract .05 depending on the need. Grab the appropriate new shim, check the measurement with the same caliper, and replace accordingly.

It's all good.
 
I really like your method Bob, simple and straightforward. My feeler gauges and micrometers are all standard though so I convert, but like you I think in terms of thicker or thinner shims. It makes conversion simple when the shims are in .001" increments.
 
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