shims

[kparkfan]

I'm doing my shim check as we speak. I have the wonderful spreadsheet from Steve. But I have just a couple of quick questions. One when entering the clearance do i enter the number that wouldnt fit such as .003 would fit but .004 wouldnt. all but one of my vaves the .003 wouldnt even attempt to go in. and the last question. i have shims in my bike marked with an X. how do i enter those into the spreadsheet to get them to convert right. first time doing my own valves. driving me nuts lol. thanks for any and all help.

[hampshirehog]

If the 0.003 fits and the 0.004 doesn't then your clearance is 0.003 and that's the figure (0.003) you should use when calculating which shim to change.

If you've got clearances too small for your thinnest feeler gauge you can do either one of two things. First assume your clearances is zero - 9 times out of 10 this will give you the right shim size, but it's not foolproof.

Second method is to find your thinnest shim and pop that in any valve bucket where there's no apparent clearance (some people have a 'favourite' very thin shim for this purpose alone). Unless you're off the limit, this will give you a gap you can slide a feeler gauge in to.

The X shims are intermediate size shims, used for getting 'optimum' clearances. However, your really need a decent caliper to measure shim thickness precisely as very often what is written on them is a bit out anyway.

[hikermikem]

The X shims are intermediate size shims, used for getting 'optimum' clearances. However, your really need a decent caliper to measure shim thickness precisely as very often what is written on them is a bit out anyway.

Ditto what Hampshirehog sez about the calipers - you simply must measure the thickness of the shims because they are not always as marked...

I think the "X" shims are generally around .025 mm larger than the stated size; for example, a shim marked 2.50X would measure 2.525 or so - you get the idea...

Don't know if others have already advised, when you put your shims back in the bucket, put the number side down - this keeps the number from getting worn off by the cam.

good luck,

mike

[Steve]

Yep, most of the X shims are .02 or so larger than the number that is also printed on the shim. What I have always done is to enter the X shims with the .02 added. If, for example, you have a 2.65x shim, enter it as a 2.67. The spreadsheet will suggest a 2.62, 2.67 or 2.72 because it only suggests a full size either way, if a change is called for, but you can still evaluate what you want to do. If you are approaching minimum clearance and have a non-X shim, you can do that, too. If you have a 2.65x and put in a 2.65, just enter that 2.65 as your final shim and all is well. The spreadsheet will highlight it in bold blue because you entered something different than what it suggested, but it will accept it. The blue is just to attract your attention.

Also, don't forget that if you are using inch measurements on the spreadsheet, you don't have to enter the decimal and the leading zeroes. If you find your clearance is 0.003", just enter 3, the spreadsheet does the rest of the math. If you are using metric mesurements, you still have to enter the decimal and one leading zero. Sorry about that.

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[hikermikem]

No doubt about it Steve, that's one nice spreadsheet you've made. Thanks for sharing it with the GSR community!!