Valve shims smaller than smallest 2.15 mm

[gert du prez]

Hi,

when doing the 'valve clearance adjustment' noticed that every shim in my 1982 GS1100 GL is smaller than 2.15 mm (which appears to be the smallest shim). Range is from 1.75 mm to 1.90 mm. They all fit very nicely, so indeed these seem 29.5 mm wide.

With the help from Mr. Steve I learned that the normal range is from 2.15 to 3 mm...that is also the reason why no Suzuki dealership is able to help me out...

I would need two 1.85mm shims and that does not exist ?

what do I have then on my bike ? other brand ? anyone ever heard of this ?

My spare bike has 8 shims in the normal range (2.35 to 2.60 mm) so cannot swap these...

I'm getting a bit anxious now...

thanks for all your thoughts on this one...

[mike_of_bbg]

Sounds most likely that someone went a little overboard grinding the valve seats at some point or another. You could try machining the ends of the valves a bit. I'll presume since you were thinking about swapping shims with the other bike that it's your parts bike. Could you just swap heads?

[gert du prez]

Sounds most likely that someone went a little overboard grinding the valve seats at some point or another. You could try machining the ends of the valves a bit. I'll presume since you were thinking about swapping shims with the other bike that it's your parts bike. Could you just swap heads?

the parts bike has the normal range (within the 2.40 mm range), it my 'normal running' bike that has the small shims.

Would replacing the head solve this ? what do I need to replace ?
- the head
- the camshafts
- the valves as well ?
something more ?

[Steve]

There are two or three ways to handle this situation:
1) Have the existing shims ground thinner to match your needs.
This is kind of risky as not every machine shop has the ability to do that kind of work.
2) Remove the head, remove the valves, have the tips ground down about 1 mm.
That will put you into shims that are well within the range of stock shims, but will require head removal.
3) Replace the head entirely, but then you introduce a bunch of other unknowns.

.

[mike_of_bbg]

The shim sets the clearance between the "fixed" components in the valve train: valves, seats, buckets, camshaft, and cam journals. If you swap heads you swap them all. If the head is the same year/model you'll be good. If you were to grind down the valves on the current head you'd have to remove it anyway.

Now, what do you know about the condition of the other head? Why is this your parts bike? Have you ever run it? Are the valves adjusted there? Ever run a compression test on it? If you're taking stuff apart you'll want to examine, clean, and lap the valves, plus replace the valve stem seals. Of course you'll also need to change the head and base gaskets after you take the head off.

Alternatively, you could swap motors if the other motor is known good. That might prove slightly easier.

Another alternative. Do a search on the forum for "shim club". Not sure how well that would work internationally; maybe you know someone in the US who would be willing to do the mailing for you. It's unlikely based on his last stock list that he'd have the sizes of shims that you're looking for, but I understand ghostgs1 has access to some equipment to lap down shims. If you're willing to wait he might be willing to lap down some of the shims you have and send them back to you. Of course you can't ride your bike during the process.

[mike_of_bbg]

ghostgs1 has access to some equipment to lap down shims. If you're willing to wait he might be willing to lap down some of the shims you have and send them back to you.

Or you could just ask him about his process and see if any of your local machine shops can duplicate it...

[mike_of_bbg]

Oh, and another possibility that I've always wondered about:

There's a "nub" on the underside of the bucket which contacts the valves. I wonder if it would be possible to machine that down some to increase the clearance? That metal should be much easier to machine than the hardened shims, and of course the buckets can be replaced without removing the head.

[salty_monk]

Any machine shop can grind down the shims... GhostGS1 Laps them but they could be put on a flat table grinder very easily.

The only important thing to remember is to make sure they de-magnetize them afterwards (the table will be magnetic) so that the shims don't start attracting to anything..... (That is also a very standard process, any decent shop could do it).

It's the least painless way... Likely the cheapest too but you will have to do it every time you need to adjust valves & there must be a limit as to how thin you can go...

Also please be sure you are measuring them correctly. Seems the previous owner did a lot of work (re-cutting valve seats then grinding down the shims etc). In my experience over the last few years I have never seen or heard of another bike set up like this.

[mike_of_bbg]

It's the least painless way... Likely the cheapest too but you will have to do it every time you need to adjust valves & there must be a limit as to how thin you can go...

Which is part of the reason I find the bucket grinding idea so intriguing in this case. If he could remove enough material, he could get the clearances back into a readily available range without removing the head/valves.

Honestly I can't remember how big those nubs were, or if I'm just imagining they were deep enough to make a difference. Fortunately all of my buckets are in a running motor

[Nessism]

I wouldn't go any thinner than 2.15 because the bucket has a lip and it's important for the shim to be taller than the lip otherwise the bucket will hit the cam.

Most likely the valve seats were reground but the valves were not shortened.

I'd pull the head, inspect the valves and seats, and then cut down the valves to restore the normal amount of clearance.

[gert du prez]

Ok, somewhere I got lost in the translation, Nessism...
probably you don't have an explanatory picture lying around ?
or a draft or hand sketch or something ?

If I take out the camshafts, can I just pull the buckets and then pull out the valves and shorten the valves if I understood you correctly ? and that will just do it ?

the engine was rebuilt some years ago (never did the valve adjustment since then ) and I have no clue what the guy did to make this a fairly good running engine...

[mike_of_bbg]

If I take out the camshafts, can I just pull the buckets and then pull out the valves and shorten the valves if I understood you correctly ? and that will just do it ?

No. To reliably machine the valves you'll have to remove them from the head, which means pulling the head. The valves go in from the cylinder side.

[mike_of_bbg]

Here. This video (courtesy of Steve in creating and BassCliff in posting) will probably be helpful in demonstrating the valve process (the video is installation, which is the reverse of disassembly).

http://members.dslextreme.com/users/bikecliff/images/valve_replacement.html

Do you have any friends who would be able to help with the engine teardown? Your questions indicate a lack of experience. It's not that hard but experience helps.

[tkent02]

Pulling the buckets and shortening the little nub should work, if any machine shop could do it. I can't think of a down side to this. I would even try it at home with the drill press and a flat diamond tipped bit, the buckets are dime a dozen so it's no big deal if it doesn't work. Anything beats pulling the head.

[salty_monk]

Just to translate.... "dime a dozen" means second hand ones are plentiful & cheap

Seems like your easiest first approach then