n00b valve shim questions - are my shims out of spec?

Hello Forum,

I have followed Fit'z valve shim guide and measured all my shims and clearances.

Some questions:

1. Can I leave shims out while removing other shims, and have some/all out while matching shims up, or does a shim need to be in each bucket when I rotate the camshaft?

2. Do shims go out of spec? I have a shim, it is stamped 270, but my depth gauge and caliper both read approximately 265mm... actually leaning to 263mm. Is this normal, and do I trust these instruments or just match up 270mm in the table and order accordingly?

3. Judging from #2 above, should I buy NEW shims, or try the shim bank method?

Thanks All!

Tim

 

BTW, My Bike is a 1982 Maxim XJ750, I hope my signature works now

 

It's not a good idea to rotate the camshaft with shims out of the buckets, it's too easy to damage a bucket or a cam lobe.

Shims DO wear; generally not enough to be measurable but it happens.

The debate whether or not to use "pre-owned" shims rages on; there is no solid answer. Some folks think it's fine; others (like me) don't re-use old shims.

 

1. This is highly NOT recommended. You risk damging the camshaft lobe on the bucket as you progress to other shims.

2. The shims are hardend, and should not go out of spec. If you have one that measures out of spec. It is possible that it may have been ground down by a previous owner. If your calipers check out fine on the other shims then it would be a good indication that the shim in question was altered. Any shims found out of spec should be discarded, and replaced.

3. The only way that a shim bank can keep going is by replacing the out going shims with the shims that are sent back. Returning damaged, or altered shims to the shim bank is not a good idea. You can get new shims from XJ4ever at a decent price.

Ghost

 

Thanks, guys.

Honestly, I have nothing to calibrate my cheapo 'instruments' with, so I'll go by the shim marking. My guess is measuring the shims is only good if the marking is missing.

And thanks for clearing up that I need shims in the buckets when rotating the cam!

I'll order new shims for now.

Thanks again!

Oh, and a HUGE thanks to you, Fitz for the detailed write up on shims, I'm a complete novice and never wouldn't have attempted this on my own without your detailed guide!

 

Here is a picture of the cheapo micrometer I have. It is on the money. I would check to see if other shims measure up with your instrument. If that one shim is not correct, it will mess you up, be careful there....make sure it is what it says.