Question regarding valve clearances

[MAC10]

I just completed a valve adjustment on my 78 GS1000C, with 95000 km on the clock. 3 of the valves are at or slightly below .04mm. A range of .03 to 08 is listed as the acceptable range. This engine was neglected, and all the clearances were too tight to get a feeler gauge in when I started.

From reading here, it looks desireable to adjust valves on the loose side. If I were to adjust the .04 clearances by changing a shim, they would then be between .08 and .09. Standard shims come in increments of 5.

Two questions: Would adjusting slightly over .08 cause any harm?
I could always do a more frequent valve check, and change shims as soon as possible to get them to .08, but I am trying to be efficient and not have to do it too often when 3 are on the tight side and will need doing sooner than the rest which are close to maximum loose. Should this matter that much, or am I being too efficient?

Are shims available in increments less than .05? I suppose I could grind some to suit maybe?

I am thinking out loud about this, trying to make sure I am thinking correctly, and not thinking my way into trouble. Comments are welcome.

[1980GS1000E]

Running them at 9 or even 10 is acceptable practice. Many here do it. Just don't let them get too tight.

[1_v8_merc]

Yeah, when in doubt, go loose.
I won't accept an .03 shim....it's already sitting on the edge, and it will become Too Tight in no time at all.

And I don't know about attempting to grind your shims down, unless you have a Lathe or a micro air grinder setup. The shims are hardened, and I don't think it's like you can take a piece of sand paper to them.lol

[Sandy]

As mentioned running a bit loose is fine and you'll find that you can actually put a lot of miles on before that .08 - .09 tightens up to where you'll need to change a shim. If it's already sitting at .04 putting the next size shim in will put you at .09 and the next time you check the valves you probably won't have to change any shims. You also don't have worry about it tighening up too much if you go a little too far between adjustments. If you leave it at .04 you will, just my being lazy approach.

[Wizard]

I just did the valves on my V4, what a pain.
Was getting a ticking noise from Cyl #3.
Thought it was a large gap. It wasn't, gap was about 2 thou.
The mixture in the cylinder was igniting and slapping the valve shut against the seat, ticking at an idle. My Bad, bad, bad,,..
It was exhaust so would soon burn the valve and seat.
If in doubt, go larger gap. Out of 16 valves, only 2 went large gap.

[Steve]

Are shims available in increments less than .05? I suppose I could grind some to suit maybe?

Yes, they are available, but you can't order them.

Suzuki installed some "X" shims that are half-sizes to get the clearance "just right". The only way to get them is to get lucky and find some in an engine. Some of us have a small supply of shims, including a few "X" shims, so we manage to get the valves right.

In your case, go ahead and go up a full size, the larger clearance won't hurt anything.

Oh, and please don't grind your shims. I am told that there is a way to do it properly, which will keep the two sides perfectly parallel, but it's beyond the capabilities of mere mortals like us.

.

[7981GS]

I still have some 2.62's available.

Eric

[MAC10]

Thanks everyone for such informative replies!

I think I have enough to get the 3 valves now at .04 up to .09. That will leave everything at.08 or .09, which should mean a worry free long lasting adjustment, a big improvement over everything being too tight. I will check the clearances again at 6000 miles as recommneded in the manual.

I used Steve's excellent spreadsheet to to track it all for future reference. For those of you that haven"t used it I can recommend it. It takes much of the mystery out of the process, along with BassCliff's guide found on his website. This project would have been much more mysterious and difficult if not for this website, and these two members. Thanks!

I found one shim marked 2.65x in the engine which I left in. I know a now retired god like machinist with his own shop, who I think would be capable of doing the kind of precise perfectly parallel grind to make intermediate sized shims, if I wanted to pursue that. I don't think I need to, and anyway while I could ask nicely, it would involve lengthy fasting and livestock sacrifice to gain an audience to pitch such a project.