This past weekend, thanks to the help of this forum and Kerry's video I did my first valve adjustment. Before my bike had a problem with idling after start up and would sometimes hang after letting go the throttle at a stop. It was getting pretty bad and I was getting pretty desperate to remedy this. After pulling the valve cover I found that my exhaust shims were too tight. Basically no clearence under a .04 feeler gauge and the bucket barely moved. I pulled the shims and found them to be 2.70 and 2.72. Yep the 7.72 is an odd one huh? Anyway I replaced them with 2.60 and 2.65 and got them to  a respectable clearence. Intakes were alittle loose, again I used 2.60 and 2.65 and again got them to spec. Putting everything back together I am finding the bike runs much better now. The job was pretty straight forward, I wanted to thanks to everyone here for the motivation to do the job myself. I kept that 2.72 shim if anyone needs one let me know

Awesome! Good to hear. I am going to tackle my first valve check this summer sometime. Not that many miles, and it's running great, so I'm in no hurry.

  -Anti 

the 2.72 is shim straight from the factory! Maybe the original shim 

Quote from: Dan02GS on March 20, 2008, 07:29:26 AM
I pulled the shims and found them to be 2.70 and 2.72. Yep the 7.72 is an odd one huh? Anyway I replaced them with 2.60 and 2.65 and got them to  a respectable clearence. Intakes were alittle loose, again I used 2.60 and 2.65 and again got them to spec.

Replacement shims come in .05 mm increments but the factory uses sizes between also, quite common.

My 97 GS had 262 and 265 shims for the exhaust valves from the factory, the intakes were never changed, never measured, and still to spec after 80k miles.

My 02 GS came with two 265 and two 258 shims, I measured them all when I pulled the head to replace a broken exhaust valve caused by a sticking bucket.

So what are the symptoms of bad valve adjustment then?

What ill affects would you notice on the bike that may indicate a need to do a valve check?

Thanks for sharing this info. Infact I have the same problem with startup, idle - basically low rpm issues. I checked for my valves and had the exact same tightness - too tight in the exhaust, the bucket could not move freely. I have ordered the thinner shims, lets see if the problem subsides . Really hopeful for a pleasant ride.

Btw does anyone know about why does a low clearance causes issues with low rpm? Is it that more energy is needed to push the piston in?

If you have tight valves, no clearance, the engine will idle rough when first started up cold.  Valve clearances will increase a considerable amount as the engine warms up and it will smooth out and run good shortly unless they are way off.  To check for tight valves in case you don't notice this initial roughness, give it a finger in the hole cold compression check.  Equally loud pops on both cylinders and valves aren't too tight.  Loose valves can be heard as noisy tappets on a warm engine or unless way too loose they might become appearant when you throw a shim.   

When I checked my valves, I had an exhaust valve that was very tight. 

After adjustment, low RPM throttle response was much better and idle was smoother.

Kasumi the symtons  were a really bad idle at start up, I would have to give it some throttle even with the choke on. Just as Jacks said, after getting it warmed up it would even out, then as time progressed it would stall at stop lights unless I kept giving it throttle. I figured it was either the carbs, valves or petcock, since Kerry had the video on the valves I went with that, also I wanted to see what was under that cover anyway. There is a lot of great information here on the site, I am really glad to have this bike for  learning  how to do stuff on. Thanks again.

Ok stupid question...HOW ELSE do I  know I need a valve adjustment? My bike does none of those things but before I left for China, she got really REALLY bad mileage. I just cleaned the filter and replaced the fuel fliter, will change the oil and spark plugs.  If by then there is still crappy mileage, what would you suggest? She has 10822 miles and has had carbs adjusted 1.5 yrs ago.  I have no tools to check the valve clearance or even do a valve adjustment. Please help!

Anyone who has done the valve adjustment: would you recommend changing a gasket/o-ring at the same time as you do this valve adjustment, while you're there?

I'm asking because I have a slight oil leak from the top of the engine that I only notice on 20+ mile rides, and it's difficult to diagnose exactly where it's coming from.  But I was hoping to just replace a gasket while I'm in there checking the valve adjustment and hope that helps; it's a reasonable chance that I'll replace the right gasket.  And I know with some gaskets, for example the exhaust headers, people recommend changing them whenever you open up the connection.

Yes, I would reccomend changing the gasket as well. You dont have to, but as long as there is a leak I think you should. When I did mine, I ordered a new gasket online from Bike Bandit, also I got the same gasket sealer Kerry used in his video. A note about the gasket sealer, use it sparingly, alittle of that stuff goes along way. 

How would you describe hanging rpm's?  When I'm at a stop with the clutch lever pulled in and I blip the throttle to about 3-4k rpm's it takes about 2-3 seconds to get back down to idle.  Is that about normal or would you call that "hanging rpm's"?

Quote from: Jerka on June 06, 2008, 07:41:27 AM
How would you describe hanging rpm's?  When I'm at a stop with the clutch lever pulled in and I blip the throttle to about 3-4k rpm's it takes about 2-3 seconds to get back down to idle.  Is that about normal or would you call that "hanging rpm's"?

Sounds like a mild case of the hangingidles. What is the rpm when it goes back down to idle? May be a simple case of bumping the idle down a little (it should be around 1200 rpm +/- 100 rpm).

I've got it set at 1300...helps me take off easier...doesn't require quite as much clutch slipping. 

Is there some kind of test or a standard amount of time that it takes to return to idle from a certain rpm?  I'm getting ready to ride to lunch and I can check it.  Like if I rev to 5000 rpm it should take x amount of seconds to return to idle.

Quote from: Jerka on June 06, 2008, 08:02:37 AM
I've got it set at 1300...helps me take off easier...doesn't require quite as much clutch slipping. 

Is there some kind of test or a standard amount of time that it takes to return to idle from a certain rpm?  I'm getting ready to ride to lunch and I can check it.  Like if I rev to 5000 rpm it should take x amount of seconds to return to idle.

Throttle speed should go down as quickly as you turn the throttle. If there is a lag between closing the throttle and rpm drop, that is the definition of "hanging" idle. Your description doesn't sound too bad because the bike still returns to idle; some bike hang around 4000 rpm and don't come down for up to 10 seconds (or until a load is placed on the engine, such as moving forward a couple of inches in 1st gear).

It sounds like your idle is already set correctly, but I'd try bumping it down a bit anyways to see if the problem goes away. Sometimes the idle is very sensitive to the setting and a hair of adjustment can make a big difference. Failing that, check for air leaks around the intake boots (spray some WD40 and listen for changes in rpm).

Have your valve clearances been adjusted recently? (Out-of-spec clearances can have an odd effect on idle)
Have you had the carbs apart recently? (Maybe an o-ring is out of place)