Valve Adjustment Theory

[SDGS1100]

1980 GS1100E, about 27K miles. The shop manual advises that the valve clearance range is 0.003-0.005". When I go to adjust the valves, should I set the clearance at the low end or the high end? What I am getting at is, does the clearance open up with use (so I should use 0.003" to set them) or does the clearance close up with use (which would suggest using 0.005" to set them). Thank you.

[Nessism]

Valves on the 8v engines tend to recess into the head thus the valve clearance goes down with use. Not sure about the 16v engines though but most likely they go down as well.

[SteveL-J]

Valves on the 8v engines tend to recess into the head thus the valve clearance goes down with use. Not sure about the 16v engines though but most likely they go down as well.

You could be right, when I checked mine (83 GS1100ED), for the first time since buying the bike, all valves were real tight -less than half the correct low end-. Either they were incorrectly adjusted prior to purchase (about 5000 miles ago) or the clearances went down.
I chose to set them at the mid point of the range.

[Mark M]

Valves on the 8v engines tend to recess into the head thus the valve clearance goes down with use. Not sure about the 16v engines though but most likely they go down as well.

AFAIK, valve clearances always get tighter over time due to the valves working into the seats. I've certainly never seen them loosen up on any bike I have worked on.

To the TS, you want to set them on the loose end of the spec.

Mark

[chef1366]

I set them at .005

[ryonker]

I believe the specs on mine are .03 mm to .08 mm or .0012" to .0030". I am aiming at around .05mm to .06mm.

This is for a 79 GS 750L

Rick

[chef1366]

I believe the specs on mine are .03 mm to .08 mm or .0012" to .0030". I am aiming at around .05mm to .06mm.

This is for a 79 GS 750L

Rick

You have an 8 valve. This guy has a sixteen valve. Apples and oranges.

[ryonker]

Thanks Chef;

I should have asked it as a question.... .05 to .06 is a good healthy valve clearance to aim for, right? (for my 8 valve GS750).

Rick

[chef1366]

With shims the highest number you can acheive is good. (in spec) Steve on this site has an Excel program for shims. PM him you email and he'll send it to you.

[ryonker]

So go for the the .08 mm? I suppose it makes sense, since the valves tend to get tighter. Except for one, mine were all slightly tighter than specs...

which I should have suspected since that's what you and all the experienced GSers are saying.

Thanks Chef!


Rick

[TheCafeKid]

So go for the the .08 mm? I suppose it makes sense, since the valves tend to get tighter. Except for one, mine were all slightly tighter than specs...

which I should have suspected since that's what you and all the experienced GSers are saying.

Thanks Chef!


Rick

if you can adjust with a shim to even .10, as long as youre not some hot rodder, you'll be better served. Lots of guys on here would put up with a bit of shim clatter and have the piece of mind that comes with good clearance. For instance, if you measured, and had a clearance of .04, the next smaller shim would bring the clearance to .09. A reading of .05 and a shim change would be .10. Id be well ok with that myself. If you were running the bike at the track, I might be a bit concerned about "floating" a shim out of the bucket if it were too loose, but not in normal street riding situations. Besides, it will get beaten in to spec pretty quick anyway.

On a secondary note, Mark M is correct. Not only do they seat, but they also tend to mushroom cap a bit. I asked Steve the other day, "Well, what happens when you run out of adjustment? What do you do then?" You by new valves and start from scratch. Guess all those 2.80s will come in handy someday after all...LOL

[TheCafeKid]

12mils to 3mils might be a bit tight, heh.

I think we all knew you meant 12mils to 30mils, though :-)

its .0012 INCHES. or .03mm. lowest spec clearance. Basicly if you're there, change it. If i have the shims to do it, i change at .05. Keeps you from having to do it later. I'd rather change them all at once if possible, but of course they dont all wear at the same rate.

[Shaughn]

its .0012 INCHES. or .03mm. lowest spec clearance. Basicly if you're there, change it. If i have the shims to do it, i change at .05. Keeps you from having to do it later. I'd rather change them all at once if possible, but of course they dont all wear at the same rate.

Fahker. Beat me to it. I deleted that post as soon as I posted it and had realized I was off by a tenth.

I work for a wire (among other things) manufacturer and we talk about everything in mils, which is a old (and non-ISO) term for thousands of an inch.
Same thing as 'thou'. And likewise .3mm ~= 12mil, and is a common size for a product I am developing. Brain read what it wanted to.

[TheCafeKid]

Fahker. Beat me to it. I deleted that post as soon as I posted it and realized I was off by a tenth.

S'all good. Personally, i cant think in inches on these bikes. As resistant as ive ever been to the metric system, when working on my bikes i cant relate in SAE, so i stick to the metric side of it. Steve confuses the hell out of me when he does his spread sheet cos he does it all in SAE. My brain sits there and tries to convert in my head, and I end up spending more time doing that than turning a wrench...lol

[Shaughn]

S'all good. Personally, i cant think in inches on these bikes. As resistant as ive ever been to the metric system, when working on my bikes i cant relate in SAE, so i stick to the metric side of it. Steve confuses the hell out of me when he does his spread sheet cos he does it all in SAE. My brain sits there and tries to convert in my head, and I end up spending more time doing that than turning a wrench...lol

Man, I can relate.
At work we specify wire over 20mils (.020",.508mm) by diameter, as you would expect.
Wire under 20mils, we specify by WEIGHT PER 200MM.
Which of course is different for the different materials we run.
So, for example, 100mg/200mm of steel wire is much thinner diameter than 100mg/200mm of tungsten or molybdenum wire.