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1981 GS1000G -- What Size Valve Shims for <0.00 Clearance?

  • Thread starter Thread starter Phaedrus
  • Start date Start date
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Phaedrus

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So, I'm chugging away at my project. Almost there. Last few orders of business are a valve clearance check/adjustment and a carb sync. Don't know the history on this bike (1981 GS1000G), but when I checked the valve clearances this eve, all are at 0.00 or less (i.e. camshaft is touching shims). Camshaft looks fine, no visible wear.

My question is, since I don't have a clearance reading and it's quite possible that my clearances could be in the negative (shaft is pushing on the shims at all times), how do I decide what shims to swap to? Do I just treat all clearances as 0.00 - 0.02?

Any insight would be much appreciated. Thanks.
 
You should start by cataloging all of your shims and going down 2 sizes
 
That's very odd that every single clearance is unmeasurable. First thing you need to do is check the shim sizes in there.
 
I was surprised myself. Odd, but not impossible, yes? Bike is an old beast. 50Kmi, beat to ****. At some point in it's past it was owned by a young kid who would drag race it. Had a bald 150/90 rear tire on it when I got it. Thing was a mess. Anyways, my understanding is that clearances tend to get tighter over time with these bikes. Could be that this hasn't had any proper maintenance in many, many thousands of miles before coming into my hands.

Will check each shim tomorrow. My concern is that since I don't have a shim kit, will have to order online, and each shim needs replacing, I don't want to start throwing dollars at shims I don't need. If I had a proper clearance reading, I could use the chart to dial in the shim size. Without, I'm kind of shooting in the dark...
 
First of all, please make sure you are measuring the clearances correctly.
Most of the manuals are rather confusing on how to do it, but you set the cams in the proper position,
then measure TWO clearances before moving anything. If the procedure is unclear, PLEASE ASK FOR HELP.

Take out your shims ONE AT A TIME.

Record the size of each one, then PUT IT BACK BEFORE MOVING THE CRANK.
There is a handy tool for doing this very thing, offered in my sig.

As others have hinted, drop a couple of sizes from what you have in there now, but after doing your inventory, take your thinnest shim out, put a quarter in its place, move that thinnest shim around to the other places to see if that is the right size. If that shim is a couple (or more) sizes smaller than the others, you will have a good idea what you will need. If it happens to be too small, it's easy enough to measure all the extra clearance to see how many sizes larger the 'correct' shim needs to be.

Will be looking for your e-mail. :encouragement:

.
 
Steve said:
First of all, please make sure you are measuring the clearances correctly.
Most of the manuals are rather confusing on how to do it, but you set the cams in the proper position,
then measure TWO clearances before moving anything. If the procedure is unclear, PLEASE ASK FOR HELP.

Take out your shims ONE AT A TIME.

Record the size of each one, then PUT IT BACK BEFORE MOVING THE CRANK.
There is a handy tool for doing this very thing, offered in my sig.

As others have hinted, drop a couple of sizes from what you have in there now, but after doing your inventory, take your thinnest shim out, put a quarter in its place, move that thinnest shim around to the other places to see if that is the right size. If that shim is a couple (or more) sizes smaller than the others, you will have a good idea what you will need. If it happens to be too small, it's easy enough to measure all the extra clearance to see how many sizes larger the 'correct' shim needs to be.

Will be looking for your e-mail. :encouragement:

.
Click to expand...

Beautiful. Thanks, Steve. Email sent :)
 
Two additional points:

1) Make sure you're clear and consistent on whether you're using units of .001" or .01mm. Unit confusion can get confusing. 'Nuff said.

2) The proper clearances are really, really tiny, and it's very easy for the feeler blades to stick together. This happens to me at least twice every valve check...

All that said, it's not unthinkable that all or most could be at zero clearance. The bike becomes very difficult to start when cold when valves get tight, so it ends up in the back corner of a shed about 12,000 to 15,000 miles after the last valve clearance check...
 
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