No numbers on valve shims?

[Guest]

Hello peeps, I'm checking the valve clearance on my '79 gs850 and I'm tight on intake valves 3&4. Meaning I can not fit a .038mm. When in position I can spin the tumbler, just thought it may be too close. I removed both shims, and being my first time, thought I would find numbers for shim size. BUT no numbers? Any thoughts? I tried BikeCliffs down load with no prevail😩. Another thing to note is the bike only has 4000 miles. Thinking they are original shims. Is there supposed to be sizing on these? Let me know watcha thinkin! Or am I just waaaaaaaay out there? Thanx✌🏼️

[SpecialK]

sometimes the numbers get worn off. If you have a vernier calliper just measure the thickness. For example a 255 shim will read 2.55mm on the gauge.

[bwringer]

The numbers are just stamped on with ink -- they're not engraved or etched, so sometimes they sort of disappear.

If you can scare up a strong light and maybe some magnifying glasses, sometimes you can hold the shim at an angle and see enough traces of the numbers to figure out what you have. Try different things, like wiping it with a film of oil, or wipe it clean, a blacklight, etc.

If that doesn't work, a digital micrometer will soon set you straight:

http://www.harborfreight.com/digital-micrometer-68305.html

(Yeah, it's HF. Mine works great, it reads directly in mm, and it's plenty accurate for shims.)

Or if you're really caught short, mic 'em with your grandpa's regular old spinny inch micrometer and do the conversion. Write the size on the shim with a sharpie and put that side down from then on. (And track what shim went where on Steve's spreadsheet).

HF's digital calipers are a good bit cheaper and can measure shims with just enough precision to distinguish one shim from another. First measure a few shims of known thickness to get a sense of how far off your calipers are and how hard you should press. Yes, the display reads in .01mm increments, but it's not quite that precise. Still, with a little practice you can tell which shim is which. For example, you might get a reading of 2.72 when you measure a 2.70 shim, so if your unknown shim measures 2.67 or 2.68, you can be pretty confident it's a 2.65.

http://www.harborfreight.com/6-in-digital-caliper-61585.html

[Brendan W]

Try bouncing light off them in different ways, wet them, dry them, breath on them, use black light and squinty eyes. Some combination of the above can bring the number up. It's generally still there or it's ghost is.
As a rule I don't rely on the numbers as shims have been ground instead of replaced and mistakes can get made on new ones.
Vernier caliper is a very good idea for shim work.

[alke46]

Just to be clear, you are looking on the bottom side of the shim as it sits in the bucket. Right?

[chuck hahn]

I never trust whats written. I always grab the digital calipers and measure each one.

[geol]

Most shop manuals will ask that you place shims with the numbers facing down but lots of folks can't read. The numbers under a cam lobe will last about 2 seconds in operation. Buy a HF digital caliper or get a similar from eBay as they don't have to be super accurate to measure a shim.

[Bemidji Ryder]

You guys rule! Have not tried any methods yet, but will be.! Going outta town for work for a couple days. On return between kids and the wife, I'll make ends meet somewhere!!! Keep ya posted!! Thanx peeps😎

[Steve]

Hello peeps, ...

... Thanx peeps

I have met MANY (well over 100) of the members on this forum, but have never seen any that looked like this:


.

(And track what shim went where on Steve's spreadsheet).

Yep, start the process by looking down there.

[hannibal]

I found that taking a picture with flash (on my phone) revealed the hidden writing...

[bwringer]

I found that taking a picture with flash (on my phone) revealed the hidden writing...

Good idea. Digital camera CCDs are sensitive to a wider spectrum than visible light, so sometimes they can pick up things your eyes can't.