Sanding down SHIMS to correct clearance..

Has anyone tried sanding or grinding of the shims just to get the correct clearance? I know this is a big NO.. im just curious what happend to your cam lubes or Bucket seats?

How much destruction did you make? If you can turn back time will you do it again???

OR

Where you succesfull and made it true the rain ..

I would love to hear your story about how a simple SHIM swap turned to a complete mess... or a true succesfull macgyver style ingenuity.

 

What if i sanded or grind the buttom part where the no. Is printed?

Would this weakend the entire shim structure? Is it build like an EGG.. were a small crack would make a huge effect?

 

A few of us on the XS1100UK forum have ground shims down without any bad results.
Some people say the shims are case hardened and shouldn't be ground, but so what, nothing bad has happened. Are they really case hardened?
But if you do it, then yes, grind from the number side so that there will be no mistake when using them again.
BTW, which XJ do yours come from? They are the same size as XS1100 ones at 29mm.

 

Mine is a 82 XJ650 4KO.. i have a little clearance problem on cyclinder #2 intake reads 0.08 the shim reads 280 but when i measured with digital caliper turns out to be 265 at best...

Engine runs smooth no starting problem no matter what temperature... very easy to start even when super hot.

I just want to be i the safe side and fix the tight valve clearance... OCD me

 

No need to sand shims.

1. Check your current clearance with the engine COLD. That means OVERNIGHT COLD.
2. Check your clearance with the chart and determine if it is in or out of spec.
3. Check what shim is needed to bring it back into spec.
4. Swap shim
5. Close the top up and go ride.

If you're not sure how to read the chart, just give us your current clearances here, for all 8 shims, and we'll tell you what shims to replace, and what shims to swap, and what valves they can shift to.

Remember, your clearance is a RANGE. So ANYWHERE in that range is in spec. It doesn't matter if y0ur on the fat side or the thin side of the range.

IN SPEC IS IN SPEC

 

Valve clearances are a specified range for a reason; the clearances change over time. Giriding shims in a shim-over-bucket arrangment will ensure that the clearance is exactly what you want it to be, for a few thousnad miles. Not worth the time and effort, unless you do not have access to any replacement shims.

 

Yes, they are:

https://www.xjbikes.com/forums/threads/another-valve-shim-swap-story-observation.29437/#post-253249

 

As I recall other posts (maybe on other fourms) found that some shims are case hardened, while others are through-hardened.
That would be a decision made by the shim manufacturer, as surface hardness would be the same regardless of the method used.

 

I ground shims on a YZF250F dirtbike once, they must have been through hardened because i only had good success on a flat surfacing diamond wheel.
A file was useless. Emery wouldnt touch them, only near the edges... Bad. And valve grinding compound on a piece of thick steel plate was taking forever.
I recommend trying to find a new shim, but it can be done.
However! If shim is only case hardened on the surface, grinding it is not such a good idea.

 

There are variations between shims of the posted size. A micrometer will tell you that. If you have a few of the size you need put a “fat” 265 in if it makes a difference . But grinding them is a waste of time. And unless you can ensure that the shim is dead square any taper will cause you more problems than it’s worth.

 

I really like the sound of the IN SPEC IS IN SPEC

I really thought when my scores like 0.11 (intake) is the LOWEST allowable clearance this would mean my engine will soon detonate

Maybe i would just check after 3k kilometers just to be sure.

 

Yes this proves to be 100% true. But have to much free time last sunday afternoon i "tried" to sand a spare shim just for fun...

So utilizing what i have drills, dremels, sanding stones, sharpening wheels, and lastly diamond grinder wheel... and about 2hours of experimenting i manage to polish my spare shim... yes just polish. I think Mr. Yamaha used some kind or really magical metal in this shims.. so i just buy 4pc thinner shims lesson learned.

 

No need to panic---
1. It's not going to blow up.

2. Your not going to have piston-valve interference. The clearance diminishes as the valve RECEDES into the head. That means it's moving AWAY from the piston and closer to the cam. The valve will only open as far as the lobe allows anyway.... it won't open farther. It will only open the same amount, just sooner and stay open longer... creating other issues.

3. No need to check at 3k. Interval check is 5k.