I'm doing my valves and came across posts on the shim exchange. The guy who was in charge, Ghostgs1, seems not to have posted since July of 2022. Did someone take over?
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Is the shim exchange dead?
- Thread starter Rusty Studebaker
- Start date
A long shot but try sending him a pm.
It depends. I took all my measurements, and cylinders 2 and 3 are the only ones out of spec. However, I have the bevel gears out (yeah, it's a shaftie) and I need to start it up and see if engine oil is coming through the trans output shaft seal into the bevel gear housing. That was my suspicion earlier. If it does, then I guess I'm splitting the crankcase and replacing the internal oil seals, which would negate any valve measurements. If not, then I will do the happy dance and deal with the shims on cylinders 2 and 3. The shims I need are 2.50, 2.55 and 2.60, which are Suzuki parts 12892-45007, 12892-45008, and 12892-45009, respectively. I have two 2.70's and a 2.65 to trade. I am waiting for a cam chain tensioner gasket which should arrive tomorrow. After I put that on, I'll put the carbs on and start her up, and see if she leaks into the bevel gear housing. Should have results by the end of the week. Thanks very much for the offer, I will get back with you with the results.
Thanks, see above message to Nessism.
Yeah Ray retired & perhaps slipped into ill health, it's been a long time since I exchanged some messages with him. The beauty of what he did for us was that he was able to use a piece of equipment he has for accurately reducing the thickness.. nobody else has that. He even used to do special sizing on request with a bit of leadtime. Let you set them exactly top tolerance. It certainly helped a lot....
Through-hardened, as evinced by the shattering of one of Steve's.
I've had to take a grinder to more than one in the past, with careful attention to detail.
FYI for anyone with a surface grinder or access to one. every .002 equals one shim size. And yes they are hardened all the way through so surface grinding hurts nothing.
Awesome. I should know whether I need them by the end of the week.
Ha! Crap, I forgot about Z1. I was just looking at Suzuki and Ebay. Thanks for the reminder.
When I had my '79 850G back in the 1980s, I religiously checked the valve clearances and over of the first 50K km (I am Canadian) all of the shims were changed.
After that, the dealer told me that the clearances were unlikely to change and so I could safely just forget about it unless the bike started running poorly in which case, bring it back. I eventually sold the bike with more than 100K km (about 63,000 miles) on it - and the last check I did showed no change in clearances since the 50K km check.
Has that been anyone else's experience or do the clearances continue to open or close-up over time?
After that, the dealer told me that the clearances were unlikely to change and so I could safely just forget about it unless the bike started running poorly in which case, bring it back. I eventually sold the bike with more than 100K km (about 63,000 miles) on it - and the last check I did showed no change in clearances since the 50K km check.
Has that been anyone else's experience or do the clearances continue to open or close-up over time?
I found the same, over long distances of mostly stable revs the clearances hardly altered. It got to the point where a check every 20K was really just an advisory.
However, when I stopped doing that and started using the bikes in what might be called normal use, the checking interval reared its head in a bad way, with a reminder that things had changed. I now check them every 6K or so, sometimes shorter or longer depending on useage.
Typically, the clearances close up with mileage. And when all the clearance is gone, the valves hang open which can lead to damage.
One of the first signs of valves starting to hang open is hard starting when hot. Keep riding, and the valve will burn and likely crack. Not good.
I don't think Suzuki did anyone a favor by specifying such a tight valve clearance range - .03-.08mm. KZ bikes, with virtually the same valve train design as the GS bikes, use more than double that much clearance.
One of the first signs of valves starting to hang open is hard starting when hot. Keep riding, and the valve will burn and likely crack. Not good.
I don't think Suzuki did anyone a favor by specifying such a tight valve clearance range - .03-.08mm. KZ bikes, with virtually the same valve train design as the GS bikes, use more than double that much clearance.
Thanks folks - some great advice here.
As for the tight valve clearances, my guess is that Suzuki was trying to keep the engines quiet and also, these late 70's GS bikes were really their first four-strokes so they were gaining experience after being a 2-stroke engine builder. I think they were also spooked after the RE5 debacle which nearly killed the company and were trying to be as conservative as possible on issues like noise and durability.
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I took your stupid dealers advice, "Forget about it unless the bike starts running poorly". That's exactly what I did. Bike started running poorly, I took the top end apart and did a valve job, and all was good again. Decided a valve check would have been waaaaay cheaper and easier... Maybe Suzuki was trying to keep you from going through this, and keep the ticking down..