Grinding Valve Shims - Opinions?

[bpreynolds]

Working to get within tolerance on the TBird Sport I recently acquired; they are shim/bucket type with several too tight.  The shims are 25mm around and I need to get a couple down in thickness from 2.70 to 2.60 or so.  I am just now finding how surprisingly challenging it is to get these locally as I've checked nearly every bike shop within city limits, all to no avail.  You'd think motorcycles don't even use them, so few around.  I've tried all local stores and nobody has size I'm needing.  Though nowhere near as divisive as an oil thread, on the Triumph board some reputable guys claim it is just fine to have a machine shop grind and buff them down to spec (then put in bucket with ground side down) while others advise not to do this.  What are opinions here?  I may just go ahead and have these ground, but then order them as per size and then swap them out the ground ones when the untouched ones arrive.  But maybe I don't even need to do this?

[dilligaf]

I've done it on Ducaties.  Not sure it was worth the effort.  :BEER:
Matt

[rocker59]

Good example of why I just mail order most things I need, these days.

You spend an afternoon of your time going to shops all over your area for something simple, only to come home empty-handed.

This happens to me all the time on the simplest of things.  Moto and non-Moto things.

I'd mail order some shims, if it was me.  Then you'll have some back stock on the shelf for next time, because your local sources still won't have them!

[Wayne Orwig]

Nobody on the board has a source to buy them?

No reason what a good shop couldn't grind them, but it sounds like a hassle.

[dilligaf]

Here you go.
So onto the web to find what else uses 25mm shims
Honda CB750, CB900, CB1000, CBX
Yamaha FJ1100,FJ1200
Older V-Max
Ventures and some older Toyotas.
Just shouldn't be all that hard except we no longer have motorcycle dealers.  We do have department stores that have motorcycles as part of the mix.  :BEER:
Matt

[jwh20]

Don't grind as this makes it way too easy to remove too much material.  Take some 800 or 1000 grit sandpaper on a hard and flat surface, like a piece of glass, and gently sand it down.  It doesn't take much movement to take off 0.001" so go easy and measure often!

[dilligaf]

Don't grind as this makes it way too easy to remove too much material.  Take some 800 or 1000 grit sandpaper on a hard and flat surface, like a piece of glass, and gently sand it down.  It doesn't take much movement to take off 0.001" so go easy and measure often!

Except keeping a 25mm disk true will be hard to do, but then I've never tried any shims that large so.......... :BEER:
Matt

[bpreynolds]

Maybe I should have been more direct in my original post.  Today is a rare Monday I have off and was thinking I'd be able to get it going today.  I've found them online quite easily but on the run up to working on the bike today I had just assumed I'd be able to call a couple places - especially the several old Jap bike shops in town (as Dilli notes, many of them use the same size) - and find them.  Certainly don't want to do anything that jeopardizes the engine just for the sake of saving 3-5 days for the others to come in; however, some guys on the Triumph board say it is fine to grind, others not so much.  

[Kiwi_Roy]

Except keeping a 25mm disk true will be hard to do, but then I've never tried any shims that large so.......... :BEER:
Matt

I wondered about that too, are they really 25mm in diameter?
I thought the shims were the same as the end of the valve stem.

[Rough Edge racing]

 The OP wants to take out about .004 of an inch? That's a lot of hand grinding on abrasive paper and being the shims are most like heat treated...a long time x the number of shims needed. But .004 is enough, in my opinion, to justify getting the proper shims...If the present shims still allow the valve to seat properly, less clearance will slightly lengthen cam timing, a little less power down low perhaps

[Tobit]

Good example of why I just mail order most things I need, these days.

You spend an afternoon of your time going to shops all over your area for something simple, only to come home empty-handed.

This happens to me all the time on the simplest of things.  Moto and non-Moto things.

I'd mail order some shims, if it was me.  Then you'll have some back stock on the shelf for next time, because your local sources still won't have them!

 :+1

Besides, wouldn't the heat of grinding affect hardness?  25mm diameter shim tells me it's probably a shim-over-bucket with the cam lobe running on the shim.  I'd buy the correct thickness and a bunch of others in various thicknesses to have on hand.

[dilligaf]

I wondered about that too, are they really 25mm in diameter?
I thought the shims were the same as the end of the valve stem.

The shims for my Ducati are caps that fit over the valve stems.  I think Jaguar used the same system.  Some automotive machine will face the valve stem to get the proper clearance.  :BEER:
Matyt

[Chuck in Indiana]

Ok, I have a surface grinder and special magnetic parallels to hold them, so I *could* grind them. I wouldn't bother though.  ;D Just order some.
 

Besides, wouldn't the heat of grinding affect hardness?

Not if your machinist knows what he is doing.  ~; That's what coolant is for.

[bpreynolds]

:+1

Besides, wouldn't the heat of grinding affect hardness?

And that's where the point of debate is on the Triumph board.  Everyone there pro the issue of grinding says it is something you need to have done by a machinist (not a diy job they say); others say/worry that it reduces the strength and durability of the shim itself.  Though I must say, in all of the discussions I've read on there, nobody once who has had theirs grinded report of failure.  

And Dilli is correct again.  These shims sit on top of the bucket like a super thick quarter, bucket slides down over stem.  I think I'm describing that correctly.

[dilligaf]

Assuming the Web information about Hondas also using 25mm shims is correct  call this number 843 554-4600.  These folks have been a Honda dealer for the past 40 years or so.  Tell the parts guy, he is new so he is learning, you are looking for such a such size shim for a Honda what ever.  Should he tell you they have none in stock ask him to check with Randy. Randy is one of the owners.   :BEER:
Matt

[dilligaf]

And that's where the point of debate is on the Triumph board.  Everyone there pro the issue of grinding says it is something you need to have done by a machinist (not a diy job they say); others say/worry that it reduces the strength and durability of the shim itself.  Though I must say, in all of the discussions I've read on there, nobody once who has had theirs grinded report of failure.  

And Dilli is correct again.  These shims sit on top of the bucket like a super thick quarter, bucket slides down over stem.  I think I'm describing that correctly.

I've never shimmed a Triumph so I can't say.  On the older motorcycle, Honda, Kawasaki, Suzuki, Yamaha and BMW,  the shim sat on top of the bucket and I was always told the shim needed to rotate just as the valve do.  That is why you will need to insure the shim stays true.  I've played with Ducati's attempting to get the exact clearances but dame if I can see any difference.  :BEER:
Matt

[PeteS]

I would guess grinding would cost many times the cost of the shim. Grinding would be done on a surface grinder. You could take a shim with cam wear marks and true it on a surface grinder.
But all this is a last resort. Way cheaper to find new ones.
My KLR was my first bike that used shims. What a PITA compared to screw adjusters on my antiques. Not that its difficult but the time spent measuring then finding them, days to weeks instead a few minutes.

Pete

[dilligaf]

True, so very true.  :BEER:
Matt

[Petrus Rocks]

I have sanded down shims for my Husqvarna.  I used a piece of glass, 400 grit wet sandpaper, and a magnet to hold the shim while sanding.  Didn't take that long and I was able to keep the surfaces  parallel.  I also bought a box of shims later.
the Huskies are very easy to shim- pull a clip and the rocker arm slides over.  Use a magnet to take the old shim out and put the new one in.  You can do it as quick as screw adjusters.

[rbond]

If the shim rode under the bucket, grinding would be OK, but riding on top, no way. It would lose some of it's case hardening and with the cam banging on it, the risk of breaking into pieces is simply not worth it. If you do it yourself, try it, but if you have to take it to a machine shop, it would be cheaper to buy new shims. IMOP.

[bpreynolds]

Took the one shim to a local machinest, really nice fellow.  He ground it in about 5 minutes, charged me $5 which is about the cost of a new shim.  And yes, gonna go ahead and buy a true one as well and replace when it comes in.

[Sasquatch Jim]

  If you must take off a lot, use a magnetic table and a surface grinder or vertcle mill.
 for smaller amounts get a flat galss palte and coat it with valve grinding paste.
 move the shim in a fugure eight pattern, clean and mic often.

 be careful,  Hey I ground it three times and it is still too thin.


 Goddamn auto incorrect.

[dilligaf]

 If you must take off a lot, use a magnetic table and a surface grinder or vertcle mill.
 for smaller amounts get a flat galss palte and coat it with valve grinding paste.
 move the shim in a fugure eight pattern, clean and mic often.

 be careful,  Hey I ground it three times and it is still too thin.

 :+1 But I've never tried it with the 25mm and large shims. :BEER:
Matt

[Chuck in Indiana]

I would guess grinding would cost many times the cost of the shim. Grinding would be done on a surface grinder. You could take a shim with cam wear marks and true it on a surface grinder.
But all this is a last resort. Way cheaper to find new ones.
My KLR was my first bike that used shims. What a PITA compared to screw adjusters on my antiques. Not that its difficult but the time spent measuring then finding them, days to weeks instead a few minutes.

Pete

This

If the shim rode under the bucket, grinding would be OK, but riding on top, no way. It would lose some of it's case hardening

no way..  ;D

[Moto Fugazzi]

Good to see you got it done today. I have a local repair shop that let's me swap shims for no charge as long as they're in spec. Shims under bucket aren't fun.
Ken

[ohiorider]

Good to see you got it done today. I have a local repair shop that let's me swap shims for no charge as long as they're in spec. Shims under bucket aren't fun.
Ken

Same here.  When I owned a 2003 Bonneville T100, the local multi-brand shop would let me swap shims at no charge.  They had a quality micrometer, so it was easy to validate thickness of shims (theirs and mine.)  I guess most of their shims came from either Honda or Yamaha bikes.

[bpreynolds]

Good to see you got it done today.
Ken

I got the shim done but that's about it.  Spent a couple hours afterwards wrestling with the cam chain tensioner after getting the shims and cams in.  Let me first say this '99 Hinckley Triumph is very well built, overbuilt like a Guzzi in some ways.  And too, I'm hardly skilled with a wrench, but even still I dunno how many times since I started this process where it's one step up, two back and I wind up scratching me head wondering how, what, why.  I'm modifying the T Bird a lot and haven't done nearly as much work on any Guzzi as I've done on this bike in the last 2 months.  But overall, things I wind up doing on the Guzzi tend to be much more confidence building than the Triumph.  I'm certain a lot of that is my lack of wrenching skills on the whole, but other things with the Triumph just make me laugh and shake my head in befuddled amusement and frustration.  I've learned and am learning a great deal but my curve is steep and just when I think I'm finally getting ahead on the job I move into something else that sets me back hours and sometimes days.

[krglorioso]

I can only imagine Brian sitting serenely at his desk at the Louisville branch library, where he's manager, hands moving busily in his lap, a sheepish smile on his face, trying to ignore the stares of his staff who are wondering just what he's doing down there.  "Oh, sure, boss..sanding shims!  That's a new one on us", while  privately muttering, "And he looked so innocent...".

Ralph

[bpreynolds]

I can only imagine Brian sitting serenely at his desk at the Louisville branch library, where he's manager, hands moving busily in his lap, a sheepish smile on his face, trying to ignore the stares of his staff who are wondering just what he's doing down there.  "Oh, sure, boss..sanding shims!  That's a new one on us", while  privately muttering, "And he looked so innocent...".

Ralph

 ;D Folks may well look back and wonder how/where the new self-love euphemism "Sanding the ol' Shim" got started.  Right here on Wildguzzi they'll say. 

[Guzzidad]

     Personally, I would use new shims. Fortunately for me, my local dealer has a box full of shims. But, another thought that may be of interest to you. Triumph makes a jig that bolts to the head that compresses the valve spring, eliminating the need to remove the cam. Just install the jig and pick the shim out with a magnet. I have the jig for the 955 but, if I'm not mistaken, your Tbird is a 900