my valve clearances are crazy

Hi everyone,

I followed the how-to (airheads valve clearance) and I have an issue.

If I go through sequentially and measure the valve clearances (1 in, 1 ex, 2 in, 2 ex, etc). Once I have them numbers, I get the new shims out, and change them all. Then I ride the bike and then check again within a week, some (but not all) are out of spec again.

So then I followed the instructions again. And I checked the clearances again. And change the shims (some of them back to last week's reading). And ride for a week and check again. And some are out again.

Then I measure all the clearances again in order. And then I measure them all again in order (not starting the bike in between). And there is a difference in the two readings. I must be going mad.

I figure I am mad.

This time, I had (e.g.,)
1 in: 0.08mm with a 260 shim (need to go to 255 shim)
2 in: 0.10mm with a 265 shim (need to go to a 260 shim)

I don't have a 255. So I changed the 2 in shim to 260. Now, without touching anything else, 1 in is 0.12mm (in spec) and 2 is 0.17mm (needs to go to 260 shim).

Ok. I am nuts.

Does anyone else have experience with this kind of thing? Perhaps there is some nuance to the shim replacement I am missing..?

 

oil under shims you reinstalled. measure shims you take out measure shime you put in.
are you measuring with lobe pointing 180 from shim?

maybe your camshaft caps are worn

 

are you using single blades or stacking blades to measure with?

 

It would help to know what the measurements were prior to the shim changes.

 

measuring with lobe 180 degrees.
Some are single blades to measure, others stacked (I have 0.01 increment from 0.04-0.1, then 0.15, 0.2).
I will get my book from the shed and can write out all the measurements

I am using the shim based on the number printed on them. I will get a micrometer and measure them