GS Valve Shim Club

[chuck hahn]

220 is as thin as they go. The only way i know of to get things into using a THICKER shim is to top the valve stem itself. Every two thousands thats taken off ADDS 1 shim size. So if say your right at 220 now then taking two thousands off will make the shim needed a 225 and so on. Note that you CAN NOT take off so much you get down to the retainers. You need 10 thousands or more above the retainers so the bucket presses down only on the valve stem itself, If you look inside a bucket youll see the round mark the valve stem leaves.

[bwringer]

I have a 2.15mm shim that is used in situations where I'm getting zero clearance. Then I can use thicker feeler gauges to get into the ballpark. You can get Suzuki OEM shims down to 2.15mm: https://www.onlinecycleparts.com/oem...-tappet-t-2-15

That said, if a 2.20 or 2.15 shim is still not thin enough, the head is coming off to see what's happening and address it. (You can also get a look into the cylinder with a cheap "endoscope" camera through the spark plug hole, and push the valve down to get a look at the edge.)

Clearance that small indicates a problem, or at least advanced wear, such as a burned valve, a valve that's too worn (the edge will be sharp instead of square), or perhaps even a "tuliped" valve. I don't think I've seen a "tuliped" valve in a GS, but I have seen the former two issues.

This can also happen after grinding or cutting the valve seats; it's pretty common to need to "tip" the valves as Chuck describes after this kind of work. Lapping the valves and seats doesn't cause much, if any change in the clearances, but grinding or cutting removes a lot more material.

On higher mileage bikes, the inner two exhaust valves see a lot more heat, and are the first to wear down to a sharp edge. New OEM valves are usually NLA, but it's not too terribly difficult to find good used valves from the outer two cylinders on a lower-mileage junkyard bike. The valve seats are extremely tough, and even if the valves are burned (usually because of leaking intake o-rings) the valve seats are usually fine.

[igoldin74]

I have a 2.15mm shim that is used in situations where I'm getting zero clearance. Then I can use thicker feeler gauges to get into the ballpark. You can get Suzuki OEM shims down to 2.15mm: https://www.onlinecycleparts.com/oem...-tappet-t-2-15

That said, if a 2.20 or 2.15 shim is still not thin enough, the head is coming off to see what's happening and address it. (You can also get a look into the cylinder with a cheap "endoscope" camera through the spark plug hole, and push the valve down to get a look at the edge.)

Clearance that small indicates a problem, or at least advanced wear, such as a burned valve, a valve that's too worn (the edge will be sharp instead of square), or perhaps even a "tuliped" valve. I don't think I've seen a "tuliped" valve in a GS, but I have seen the former two issues.

This can also happen after grinding or cutting the valve seats; it's pretty common to need to "tip" the valves as Chuck describes after this kind of work. Lapping the valves and seats doesn't cause much, if any change in the clearances, but grinding or cutting removes a lot more material.

On higher mileage bikes, the inner two exhaust valves see a lot more heat, and are the first to wear down to a sharp edge. New OEM valves are usually NLA, but it's not too terribly difficult to find good used valves from the outer two cylinders on a lower-mileage junkyard bike. The valve seats are extremely tough, and even if the valves are burned (usually because of leaking intake o-rings) the valve seats are usually fine.

That is some invaluable information. So my head was serviced my a shop, and now my exhaust side seems to be way off. I tried and ground one old shim down to 180-185 and it still seems as not thin enough. The shop did not mention any excessive wear on valves or valve seat. I am going to contact them next week and ask for more information or any advice. That’s really worrisome.

[chuck hahn]

GS valves cant be ground far as ive bben able accertain. No info in service manual. As i stated above you can top the stems but be sure to stay 10 thousands or so above the keepers. And for every 2 thousands thats removed equals one shim size. Wish i had a part number for the seats but maybe someone here has that info. If so please pass it along.

[Nessism]

GS valves cant be ground far as ive bben able accertain. No info in service manual. As i stated above you can top the stems but be sure to stay 10 thousands or so above the keepers. And for every 2 thousands thats removed equals one shim size. Wish i had a part number for the seats but maybe someone here has that info. If so please pass it along.

Suzuki doesn't sell valve seats. It may be possible to replace them with an aftermarket part, but the cost will exceed purchasing a serviceable head.

Jay, owner of APE, mentioned on the KZ site, that they tip valves and even keepers sometimes, to keep the head in service. I don't know the limits, but there are ways to keep even a worn head out of the scrap bin without changing seats.

[chuck hahn]

True enough ED. There has to be a good 30 thou above the top of the keepers so for each 2 thousands vequalling one shim size you can take a heck of a lot off before getting to keepers. The idea is to keep the stem above the top of the keepers so the bucket doesnt hit them and throw them out. I CRINGE at the thoight of hearing that happen!!!!!

[igoldin74]

Please pardon my ignorance but I am not quite familiar with the glossary here:
what is keeper? What means tipping valve?
also, is there a way to measure the clearance between an empty bucket and cam? Running the engine with exhaust side out of specs - what are the consequences?

[chuck hahn]

keepers are the half moons that fit into the groove at the top of the valve stems... a wedge that KEEPS the top cap locked in place trapping the springs. TIPPING OR TOPPING is removing material from the top of the valve stem making it shorter, Thus making bit shorter increases the gaps when measuring between a shim and the cam shaft. So if youre already at the lowest shim made then tipping the stem will now allow the use of a thicker shim. And as i stated, every 2 thousands taken off adds 1 shim size. Example... If say your at ,03 MM clearance with the 2,15 shim in the bucket. So you take 2 thou off the stem..you now have the clearance to put in a 2.20 shim
BUT whenever i have a stem ground i usually take 10 thou off which lets me now use a really thick shim and this then allows me to just resume normal clearance checks and know i have plenty of other shims that will fit when te time comes. make sense to you?

[igoldin74]

keepers are the half moons that fit into the groove at the top of the valve stems... a wedge that KEEPS the top cap locked in place trapping the springs. TIPPING OR TOPPING is removing material from the top of the valve stem making it shorter, Thus making bit shorter increases the gaps when measuring between a shim and the cam shaft. So if youre already at the lowest shim made then tipping the stem will now allow the use of a thicker shim. And as i stated, every 2 thousands taken off adds 1 shim size. Example... If say your at ,03 MM clearance with the 2,15 shim in the bucket. So you take 2 thou off the stem..you now have the clearance to put in a 2.20 shim
BUT whenever i have a stem ground i usually take 10 thou off which lets me now use a really thick shim and this then allows me to just resume normal clearance checks and know i have plenty of other shims that will fit when te time comes. make sense to you?

Yes, understood. What it the process of tipping the valves? How is it typically done?

[chuck hahn]

Surface grinder, lathe, or a valve grinding machine like my buddy has. They gotta be ground at an exact 90 to the stem itself.

[bwringer]

There's a larger point here: if you're out of shim room, SOMETHING AIN'T RIGHT. Tipping the valves isn't going to fix anything; you need to figure out what's going on here.

You can start by taking a look at the entire perimeter of he valve with a bore scope and/or pulling the head off to see what's going on.

The only circumstance where tipping the valve would make any sense is if the engine has been apart before and someone went too far with a valve seat grinder. (And that's assuming the grind was otherwise done competently... often not a safe assumption.)

You can't tip the valve in situ, so you're really not in for any more work to go ahead and pull it off and see what's wrong. Again, SOMETHING IS WRONG. Tipping is a workaround for a very specific and frankly unlikely situation.

My bet would be that this valve is burned; its probably got a gully worn into one edge by hot gasses. At the very least, it's worn to a knife edge. Either way, it will need to be replaced, the valve seat carefully inspected, and the valve and seat lapped.

[Nessism]

Is the Shim Club dead? It seems that Ray hasn't been back to GSR for a year. Does anyone have any recent experience?

[chuck hahn]

I PMed him about a year ago willing to donate about 30 shims i have on hand but never got a response. I wish i had the time to take up the club as it was a great resource i had used countless times. I now have access to a surface grinder so i can pretty much make what i need. Has anyone ever texted the rockwell on a shim befor and after surface grinding to determine if the grinding affects them?? Just curious about that aspect

[bitzz]

Pretty sure they're case hardened, otherwise they'd shatter

[Rich82GS750TZ]

I could be mistaken but I believe I read here somewhere that Rapid Ray was removed from the forum a few months ago. My apologies to Ray if I’ve got my facts wrong.