Mystery shim identification?

[steve murdoch]

A bunch of these shims were included with a recent purchase.
29mm diameter and 3 different thicknesses with markings indicating 2650, 2675 and 2700.
Any ideas? Never seen any shims with holes in them either.
Kawasaki perhaps? I know they are 29mm instead of the Suzuki 29.5mm.

 

[limeex2]

Odd ball size shims come from the factory. They were done by hand back then and were perfect when they left the factory hence the odd sizes. Not sure about the hole though. Aid for install?

 

[Steve]

Yes, Kawasaki and some Yamaha had 29.0mm shims. The thickness is not all that unusual, just think of them as 2.65, 2.65x and 2.70 shims. Have never seen a hole drilled in a shim before. Might be to relieve suction when removing one, but I have never had THAT much trouble doing so.

.

 

[steve murdoch]

Thanks for the input, Gents.
I don't have an immediate need for these but would the slightly smaller diameter be a problem if i used them on my GS?

 

[Gumpster]

Huge problem, do not use these in a GS.

 

[Brendan W]

Suppose I said, Hell yeah, no problem. I put one in and the bike revved straight out to the redline. I put a bit of Moly paste in there just to glue it down a bit. Been four years back. Bikes done a hundred miles or more since.
Feel any safer?

Back in the day this was a hot topic. Mechanics at local dealer were even putting it about that it was fine. That probably means there was a lot of it going on.
You'll always hear people letting the world know how smart they are but you never hear about their screw ups.
Recently the shop was being wound down and the old boy was selling off NOS. I went looking and he offered me Yam shims for the GS. I took them ,never know what bike will cross my path up the road.

 

[Steve]

... would the slightly smaller diameter be a problem if i used them on my GS?

I can't guarantee they won't work, but I wouldn't advise using them. :-k

They are only half a millimeter smaller, but when they start moving around at up to 75 times per second (at 9000 RPM), ... well, let's just say that things could get "interesting".

I have two boxes of shims. One is 29.5mm for my GSes, the other is 29.0mm for my previous Kawasakis. I am hanging on to the Kaw shims because, as Brendan says, you never know what's going to be coming into the shop.

.

 

[chuck hahn]

1/2 mm smaller than 29.5 will allow them to 'kick up' as the lobe rolls on and off. I wouldnt advise using them where a 29.5 is required.

 

[steve murdoch]

Excellent advice, fellas.
Now i will have to start looking for a Kawi project to go with the shims. haha.

 

[Agemax]

1/2 mm smaller than 29.5 will allow them to 'kick up' as the lobe rolls on and off. I wouldnt advise using them where a 29.5 is required.

Totally agree, i would not risk using them, the consequences will be expensive!

 

[bwringer]

I found three Kawasaki shims in the last GS850 I worked on.

They were quite loose, and there was little to no oil surface tension holding them in place as you see with the correct shims.

AFAIK, the engine was run for some unknown number of miles with these in place.

But it's just a stupid, stupid, stupid idea. The risk/benefit just isn't there. Sometimes a shortcut makes sense. This is not one of those times.

Unless the volcano is rumbling and it's your only ride outta town, I just don't see the point of installing the incorrect shims, and the potential downside is huge.


Anyway, I have no idea what those holes could be for.

 

[fastbysuzuki]

Hi, I have just beeen reading an article by Pip Higham regarding tuning the gs1000 in its heyday he talks of the master move by suzuki to have pops yoshi onboard for racing development and some of the stuff that followed, pip was campaigning a gs750 then the gs1000 stating that due to pops development they were runnning shim under bucket and the Shims were lightened via a drill hole I was thinking you may have come across a piece of history in a way.

 

[Sandy]

Hi, I have just beeen reading an article by Pip Higham regarding tuning the gs1000 in its heyday he talks of the master move by suzuki to have pops yoshi onboard for racing development and some of the stuff that followed, pip was campaigning a gs750 then the gs1000 stating that due to pops development they were runnning shim under bucket and the Shims were lightened via a drill hole I was thinking you may have come across a piece of history in a way.

I'm pretty sure the shim under bucket shims were a lot smaller diameter. Not 100% sure about Pops shims but all the production stuff was pretty small as it only had to be large enough to cover the top of the valve stem.

 

[GregT]

Hi, I have just beeen reading an article by Pip Higham regarding tuning the gs1000 in its heyday he talks of the master move by suzuki to have pops yoshi onboard for racing development and some of the stuff that followed, pip was campaigning a gs750 then the gs1000 stating that due to pops development they were runnning shim under bucket and the Shims were lightened via a drill hole I was thinking you may have come across a piece of history in a way.

Pops came on board after running Kawasaki Z1's - and a prototype big bore Z650. He brought the shim-under setup from the Z650 - which pretty much swaps straight into the GS heads. Those shims are 12 or 13mm OD from memory - can't be bothered going out and measuring one. Too small for any lightening holes when on top of a 7 or 8 mm valve stem. But a lot of the early Yosh race buckets had lightening holes down the sides. Pip may be getting mixed up - or misquoted.

 

[fastbysuzuki]

Pip may be getting mixed up - or misquoted.

No Pip was neither when I read that he said the buckets where lightened I put two and two together to make five thinking the shims had been lightened my fault not his.

 

[hillsy]

Those drilled shims should go straight onto a keyring

 

[fbody_mike]

Maybe a machinist can chime it, but wouldn't those holes have had to be drilled before the shims are hardened? From what my experience the shims are brittle like glass and I would think it would take a lot to drill them, but I have never tried.

 

[storm 64]

Maybe a machinist can chime it, but wouldn't those holes have had to be drilled before the shims are hardened? From what my experience the shims are brittle like glass and I would think it would take a lot to drill them, but I have never tried.

Not necessarily, a EDM (Electrical Discharge Machine) could make a hole in the hardest of steel. It uses a graphite electrode to "burn" a hole through it. The EDM is a very popular machine in the extrusion die business.
Also the EDM machines go back to the 60's. So Pops could have very well used it��

 

[GregT]

Not necessarily, a EDM (Electrical Discharge Machine) could make a hole in the hardest of steel. It uses a graphite electrode to "burn" a hole through it. The EDM is a very popular machine in the extrusion die business.
Also the EDM machines go back to the 60's. So Pops could have very well used it��

Yeah, an EDM will do it - but a carbide drill would probably also do it. Guy here was using carbide drills to put holes in bearing races for locating pins.
I've used carbide tips to machine hardened shafts too. Late 5 speed box into an early 4 speed Aermacchi (HD Sprint) needs the layshaft ends machined to suit the 4 sp bearing sizes...
Lightening the buckets is a bit trickier. They are hardened right through and the skirts (sides) are brittle. To do them I'd think you'd either get them unhardened from Suzuki (or their supplier) or soften, drill and reharden.
Wouldn't surprise me if Pops got the idea from Jaguar race stuff. The yanks were drilling holes in everything in a Jag engine in the '60's - but those buckets are chilled cast iron so a bit nicer to work with....