Valve Shim Replacement; New or old?

Checked the valve clearances in my xj700 and two inlets had incorrect clearances. One needed +5 and the other -5. Just so happened that swapping the shims from each valve solved both clearances perfectly.

Now my question is can old shims be used or must the shims be replaced with new ones?

Oh and by the way I used the ziptie method of holding down the valves as mentioned on this forum. Perfect job.

 

There is a raging debate over this.
I will just say that I reuse my shims and have had no problems.
I will encourage you to make your choice based upon your understanding of the issues both sides present. Both sides agree the shim is hardened but there is a divergence about how durable it is or how deeply the hardening penetrates into the shim. Check out the debate by doing a little search for the topic Valve Shim reuse.

 

Thanks for that. I had a feeling this question would bring up "issues" as I know valve parts in general on engines should not be interchanged. in other words using one spring on another valve when reassembling. However this is a different situation to the way some parts wear.

I see Chacal is all against the idea in one of the threads and rightfully so, he sells them. But I do see his point, they probably can wear and in fact one of the shims I swapped left me doubting it was actually the original size as I got a different clearance to what I was expecting. In fact if it was the size marked, it shouldn't have worked but I chanced it anyway. :roll:

But if inaccurate sizing is the only issue, then I'll leave it in there. Once the clearances are right, that's all that really matters. As for increased wear, well I service my bikes regularly so I can just give it that extra bit of scrutiny next time the valves are checked.

 

I just move ½ my shims around BUT had to buy one from my local Yamaha

OUCH $22.79.

I have swapped them for years on several motorcycles.
Didn’t even know there were issues with swapping, till now??

Sorry chacal it’s MY PayPal issue, LOOKING forward to receiving my colortune, the check cleared.

ab

 

the aftermarket shims chacal carries are less than half the price of OEM and cheap insurance.

I ride and maintain two (soon to be 3) XJs and do NOT believe in shim swapping and here's why:

Did you ever notice that the shim/bucket rotates when activated? The cams have a slight angle to them to create this rotation. The shims do wear, quite evenly but they do wear. My concern is that a shim that's been "worn-in" on one cam lobe may very well NOT be a good "fit" for a different cam lobe. These are 25+ year-old 10,000 rpm motors, and I personally would rather spend $8 apiece for new shims than spend gawd knows how much to repair the damage a spit shim would cause at 9Krpm.

For me it's simply not worth it, I've got too much time and effort into my bikes to chance destroying one to save $8.

 

There is no such thing as wear that can't be measured. If you measure your shims and they exhibit no wear after 10,000 miles on the bike, why would you not re-use them?

It doesn't get any simpler than that.

 

but they DO exhibit wear; you can see it, there are distinctive patterns to it. My concern is in then moving that visibly worn shim to a different cam lobe than the one that wore on it in the first place.

 

I meant exhibit measureable wear. The surface wear you are describing is nothing more than a polishing action from the parts rubbing together. The matched hardness of the working surface prevents wear that would adversely affect performance. Unless there is something wrong. But if something was wrong, it would make a measurable difference.

Fact of the matter is, we don't have to change valve shims because the shims wear, we have to change them because the valves train changes.

 

Agreed. "Matched" being the key word. A nicely-polished shim may NOT "match" a cam lobe other than the one that polished it; I'm not willing to take that chance with my motors.

 

Matched as in equal hardness, so one doesn't destroy the other. Not matched as in worn to each other. They don't wear to each other. If the shim wore at all, you would break through the hardness coating and it would all go to hell with a quickness. It doesn't matter what it looks like. If there is no measureable wear, it hasn't worn, or mated, or matched, to anything.

 

can't say for sure but i doubt shims are surface hardened
to heat steel enough to change the hardness there's a chance of shrinkage or warping, it's just hard steel all the way thru
has there ever been a post here about a engine failure caused by a valve shim ?.....i don't think so
Dermont, if your measurements don't seem right, check the 180 degree cam lobe alignment, not 170 or 190, it matters
the shims are right

 

You don't have to excessively heat the metal to surface harden it. There is a combination of chemicals and heat that you use to harden it. Not just super high heat.

 

Oh this thread is getting juicy :lol:

Okay I mentioned that it appears one of the shims could be worn even though I must say now that there is no visible evidence of this. Here is how I came to the what I'll say suspiciion.

The valve in question when measuring with a feeler gauge didn't even have .05mm clearance (sorry for the metric version) as I couldn't get the .05mm feeler gauge through. The shim was a y270 (assuming this is 270mm)

Swapping to a y265 shim (-.05mm of a difference) to it and all of a sudden I have .15mm clearance, a loose .15mm. So my assumption is if the shim was right, I still shouldn't have been able to get a .15mm gauge through it, only .10mm.

Now having said all this I've never been what you'd call a maths wizard so I don't really stand behind my figures :lol:

 

Sure glad you cleared that up
BECAUSE if you have visible/measurable (maybe a little polishing) shim wear then you have cam wear and that ain’t good.

ab

 

I wouldn't stand behind 270mm, Dermot. 8O

 

Maybe 2.70mm Eh ?

So have you measured the Y265?
Sounds like it's worn or marked wrong...

 

Recently had my head off, and while I was at it I checked all of the shims with a digital caliper. They were all within spec to within the tolerance of the caliper (about .01mm).
However, I do not know how old these shims are, and the engine may be at least 30,000mi old itself.

 

this is a very interesting debate.

my question is this, the shims are not locked in place within the
bucket. therefore as they move around under the cam lobe it would
seem that the chance for uneven wear would occure. in other words
high and low spots would develope and then shift due to tolerances
from the sides of the bucket. the shims must resist this type of
wear or otherwise the cam lobe would start to bind against the
uneven shim. am i wrong?

so it seems to me the wear would have to be so minimal that you could
reuse a shim for at leased a certain amount of time without repacement.

ok, i'm ready to be told i'm full of BS lol.

 

No BS from me.
The only time I buy shims is when I don’t have 1 that will fit.

Here’s a link to XS11.com they have a shim swapping library.

http://www.xs11.com/forum/showthread.ph ... light=shim

ab

 

When I first started riding my original xj650 28 years ago, I had all the services done at dealers and bike shops up to 90,000 kms, when I finally hopped off it ,still going strong. I never found a workshop that didn,t re-use shims. During my current rebuild of this bike,I put a micrometer over all the original shims,and found virtually no wear on them. So ,I would suggest,measure, and if different from stated size,discard,if not re-use

Cheers, Murray

 

A problem with a shim pool- - the other guy in another state used a magnet to help remove the shim, and you might install a slightly magnetized shim. Just enough magnetism to hold the fine iron particles that circulate in your oil that are made by the chains and gears. Not enough magnetism to pick up a nail, so you can't test it.

I think I can find seven bucks.

 

+1 That too.

 

hmm...I was real slow on the uptake on this one. Yeah always had a problem with putting my decimal point in the wrong position. :lol:

Haven't measured the Y265 as I don't have a micrometer. Next chance I get I will take it out and get it measured somewhere.

 

where did all this magnet stuff get started anyway ?
here's the yamaha book, what's that guy using ?
60 psi of air works the best

 

The "magnet stuff" got started because it's a genuine concern. I saw that in the Yamaha 650 book, but in one of the other Yamaha manuals (or tech bulletins, I'd have to dig it out) they warn AGAINST using magnetic tools for exactly the reason mentioned.

It IS a genuine concern, and a bad practice.

 

You can use Shims over and over and over.
The Cam Lobe will wear down before the Shim deforms.

A couple of Yamaha Bike did have Cam Lobes prematurely wear.

Some other Sites run a Shim Pool.
You send-in the one you that needs changing for the one you need to change too.

 

The cam lobes are ground at a slight angle so they turn the shims / buckets & wear evenly.

 

I have seen other motorcycle maintenance manuals that actually state to use a magnet.

Some reasons I think it isn't a problem:

1. The oil that gets pumped to the top is post filter oil
2. If the magnetism is so small that it can't be measurable, it isn't strong enough to prevent the metal particles to be washed away by the pressure action of the oil moving through.
3. If there are fine particles getting trapped, they are so fine, they can't really affect anything, except to maybe adjust your clearance to an almost immeasurable amount.
4. Those fine metal particles aren't harder than the hardened surfaces of the cam lobes and the shims. If they were, they wouldn't be experiencing life as wear particles in the first place.

Just some random thoughts.

 

I'm also wondering if a tape head demagnetizing tool could be used to counteract any possible effects of this slight, possible immeasurable amount of magnetism.

 

It's just as easy to simply not use a magnet. I use hemostats myself.

And I won't re-use shims; false economy as far as I'm concerned.

To each his own.

 

My random thought- - drop some cheap-O magnets in your filter !!

 

Doesn't heat destroy magnetism ? Is the heat of the motor not enough to kill the magnetism ? Just wondering.

 

Since this thread started last year I've had the VC off
to replace the gasket and replace a couple of shims.

After fighting with the hemo's (cheep ones that lost a bit
of the chrome plateing at the tip), I tried the pen mag.

The shim slipped right out and I had it off the mag in less then
a sec. There is no way that miniscule amount of contact or
exposure is going to create enough magnitisim to amount to
a hill of beans-metal or organic lol.

After checking a new shim with the same # old one with the
calipers the diff was under .002. NOW- go close your calipers
then open to .002. try and look at how far the jaws have moved
apart then see if you still believe you need a new shim.

2 cents spent for the day.

 

My concern is not the possibility of .002 (inches or mm?) worth of wear, but that the wear could be: unique to that particular bucket; or enough to have compromised the hardness of the shim.

Since I do quite often hit 10K rpm, I like the peace of mind that new shims bring.
Unmagnetized ones.

 

UN-subscribed

 

Ok you got me there as I like my motor and rarely take her
over 7k.

If the cam lobe made a low spot (of significants) on a shim,
then at some point you would run the risk of that low spot shifting
to a place under the lobe causing binding.
Having a cam deside to stop turing at 10k would not be as much fun as
it sounds. :wink:

 

It's not the cam stopping turning-- it's the shim suddenly being spit out of position... and the potential resultant damage.

7K is where the fun begins these motors are happier at high rpm than low. I won't do anything to compromise that capability.

 

I think you guys are reaching a little too far with Shim scenarios.

Removing a shim with a Magnet doesn't magnetize the Shim.
The Shim Material is Harder than the Cam Lobe.

Please don't scare the readers and have them think that they are going to have their Bike break down if they removed a Shim with a Magnet.

It won't.