I was adjusting the valves on my recent purchase ('77 GS400) and the clearance on all four was under .038mm which is the smallest one I have. Could I be doing something wrong or could they really all be tight? Anyway, assuming they are really tight, I couldn't get the shims out. I don't have the tool of course, so I was attempting other methods. Does anyone have some pointers on how to get the shims out that don't involve the tool? Thanks.

Also, I heard a tapping sound when I last ran it, it occured at idle and was very noticeable. What could this be? Thanks

The tool is your friend.I've tried other methods and gave up.Went to dygver and watched him with the tool.Went that night and ordered one.038mm isn't tight.Tolerances are .03 to .08mm.Tapping in the top end could be cam walk or low oil flow to the head,which happens at low rpm.

Well the .038mm wouldn't fit in at all, so that means they are tighter than .038. I couldn't find a set with anything smaller. Guess I will be ordering the tool.

I assume this means that the valves probably haven't been checked often if ever....bike has 13k on it.

My thoughts on changing GS500 valve shims:

http://img.photobucket.com/albums/v443/jcp8832/ValveShimTools.jpg

Noise could be a tappet or the camshaft end play knock so common on the GS500.  A tappet noise would be high frequency and kinda clicky sounding and the camshaft noise is low frequency and kinda a thud type sound.

Shouldn't have a tappet noise if the clearances are as tight as you found unless you have a sticking bucket problem.  Try turning the buckets with your finger tip with the cam lobe turned away from the shim.  Should turn freely if there is any clearance and the bucket isn't sticking.

Check your oil flow to the top end.  With the valve cover off, cranking the engine with the starter should cause oil to overflow onto the floor rather quickly if the oil flow is normal.  It should be with only 13k on it.

thanks jack, the noise is more of a deep thud. the bike starts very easily and runs nicely aside from the noise. I've only run it for a few minutes since its been in my presence and I figured better do some maintenance now.
I just ordered the shim tool so soon I will get this all done.

Just to make sure you're not overlooking the obvious, are you making sure the cam lobe on the shim you're checking is pointing 90 degrees away from the shim surface when you check it?  If not, it will be too tight for sure (but you're not measuring the real clearance!).

QuoteCould I be doing something wrong or could they really all be tight?

Running the engine hot/lean all the time could cause clearances to diminish fast. Mine only has 16K and I'm looking at little to no clearances left too. Richen up your fuel mixture.
Also, you can take the camshaft off, but you'll have to take the cam chain tensioner out too and reset the timing when you put it all back together. It's a little more work, but necessary if you absolutely can't get the shims out. I had to do it recently and was able to put it back together right the first time.

I ran my 97 GS500E hot and lean (no rejet) for 80k miles and JP ran it to 88k before he swapped engines and the intake valve shims were never changed and valves remained at .002 and .003" clearance.  The 02 is going the same way, intake clearances still same at 59k miles.

http://img.photobucket.com/albums/v443/jcp8832/valveclearances.jpg

Is there a reason people don't loosen the nuts holding the camshaft on to make it easier to slide the shims out? If you just loosen them and don't remove the whole camshaft, wouldn't you just tighten them back down and everything would be okay? What am I missing?

Quote from: pjm204 on May 25, 2008, 05:58:37 AM
Is there a reason people don't loosen the nuts holding the camshaft on to make it easier to slide the shims out? If you just loosen them and don't remove the whole camshaft, wouldn't you just tighten them back down and everything would be okay? What am I missing?

You want to avoid loosening the camshaft if you don't need to. When you tighten down the camshaft, you need to draw down all the bolts evenly. If you don't it is really easy to strip the threads out of the aluminum head.

Get the tool, or use a screwdriver to depress the bucket so you can pull the shims. That's how it was engineered to work.

Yea, I ordered the tool since right now I have 4 GS's, I'll probably be using it pleanty to justify the purchase. I couldn't get the bucket to depress with a screwdriver, hopefully I can figure the tool's proper usage out.

Quote from: pjm204 on May 25, 2008, 08:04:32 AM
Yea, I ordered the tool since right now I have 4 GS's, I'll probably be using it pleanty to justify the purchase. I couldn't get the bucket to depress with a screwdriver, hopefully I can figure the tool's proper usage out.

I found the job to be much easier with the valve tool than messing around with a screwdriver. With four GS motorcycles, you won't regret buying the tool!

Use of the valve tool is pretty straightforward. If you haven't seen it yet, Kerry's video describes it pretty well. There is a link to this video on the wiki:
http://cgi.stanford.edu/~sanjayd/gs500/Maintenance/CheckValves

Good luck! Let us know how it turns out.

Quote from: pjm204 on May 25, 2008, 05:58:37 AM
Is there a reason people don't loosen the nuts holding the camshaft on to make it easier to slide the shims out? If you just loosen them and don't remove the whole camshaft, wouldn't you just tighten them back down and everything would be okay? What am I missing?

You will loose the cam timing and it's a pain to straighten it out after words.

yea, once I get the tool I will probably check the valves on the GS that I ride(2001)....the 1977 is one I am working on to sell, then I have a '78, and my brother has a '99. I need to take the tank off anyway to do a little fine tuning of the carbs. I jetted them but didn't add any washers under the needles. Might play with the mixture screws a bit as well, the 2001 just hit 3600 miles today so it is definitely due for a check on the valves.

I got the tool today, I think I'm in love.....made the job soo easy. I had the job complete in about 45 minutes not counting the time to the shop to get shims. Now all four are in spec and it started up like a champ.