Hi,
I'm doing the valve clearances at 30.000km on a 2009 faired model. Against my better judgement this is the first time I've checked the clearances on the bike, in fact having bought the bike at just 3000km I believe this the first time they've ever been checked or the valve cover has been off. Anyway-The bike has been experiencing idle problems for first 10 minutes or so of operation for about 5000k which I've just "lived with" because it's not too hard to deal with, but coming up to 30,000km I have checked the clearances and found in the first position with the notches facing each other on the cam ends as described in Haynes manual I was getting zero clearance on the right hand exhaust valve and 0.10 which is a bit wide on the left hand exhaust valve. I checked the shim width for the right hand exhaust which turned out to be 278 and replaced with a 270 shim. this time I checked the clearance with the cam lobe pointong directly away from the valve, which is a little bit different than the position you end up with when the cam notches are facing each other and I still got a reading of zero... in other words 0.03mm feeler guage not going in. I ended up going all the way down to a 255 shim when I was able to measure 0.07mm clearance which was finally in spec which I was happy about, but here's the problem. This measurement was taken when the cam lobe was facing directly away from the valve (what I'd assume was the the valves most seated position) but when I took the measurement again from the Haynes manual position which was maybe 20 degrees off the furthest position I get a clearance of 0.20mm which is kind of massive..
I assume I should go with the smallest clearance measurement but I'm a little concerned the discrepancy shows there is something amiss. I would have thought if anything the valve clearance would decrease the further from the fully closed position the valve became, but really they should remain consistent until the valve opens.
I've tried turning the engine over by hand several revolutions to allow the shims and followers to settle but continue to get the same problem. 0.05mm when furthest away and 0.20 when in Haynes manual position. The next step I'm thinking of taking is the release the retaining caps on the cam and rechecking the cam to follwer (or bucket) seating a bit more closely.
Hopefully this isn't an indication of a bent cam or valve, I suppose it could also be an incosistently worn cam lobe but there is no obvious sign of that.
I may check the other valves and see if this inconsistency occurs with them as well.. maybe that would help clarify.
Well, I hope someone with more experience with these engines can explain what could be the problem here- if it is normal, or what to do from here.
Thanks, hope someone can help.

Well, for the record- I measured some of the other valve clearances and there is also a bit of variation with them too. It seems to be more so on the exhaust valves.
Put the whole thing back together and not only has it fixed the idle problem. It's running better than ever. Seems to have quite a bit more power (any wonder now the exhaust valve is sealing properly)
Quite satisfied and happy with the job.
Just need to go back and replace the rocker cover gasket... also looks like the generator cover gasket has a leak.

When you remove a shim, the bucket will fill with oil. You can read 0 clearance. BTW You're using a car feeler gauge set ? We have valves that need 1 to 3 thousands of an inch. And the thinnest gauge we can find in the motorcycle kit is 1.5 thou.
You run huge clearances it will be OK but make a racket, and increase the possibility of shim getting out.
Typically we run them a bit loose. 3-5 thou on the intake and 4-6 exhaust. Not 10 and 20 thou.
Cool.
Buddha.

Can Buddha repeat the advice about oil on shims during valve check. Check, insert, get false reading, then what? Spin it a while then check again?

I am soon to revive my 89 white with belly pan.

Quote from: johnny ro on November 27, 2022, 07:48:49 PM
Can Buddha repeat the advice about oil on shims during valve check. Check, insert, get false reading, then what? Spin it a while then check again?

I am soon to revive my 89 white with belly pan.

I usually dont recheck again until after a ride (or dont recheck it at all). Maybe a few rotations will get the oil out. Not sure.

The process for me is - measure the clearance, pull the shim if needed do the math and put the right shim in. If its only slightly loose I'd not touch it. If its slightly tight - like how would you even know that, the thinnest feeler gauge is 1.5X the tight end of the spec. Basically your effective range is 1.5 to 3 thou. I'd go with over 1.5 thou at the tightest and well if you swap in a shim at 3 thou, you're going to end up under 1, so 4 thou is the loosest you can swap a shim for a thicker one. Basically at 4, you're still safe. You run into the loud noise looser shims make past 5 thou. However other manufacturers basically spec the same type of motor (80's Yamaha FJ air cooled motors - near identical to the GS that you can in a pinch use yamaha shims in the GS but not the other way around) specify 3-5 intake and 5-7 exhaust. Good numbers if you want to copy that IMHO. But I'd say 2-5 on all may be fine too, I've run that and not had a problem.

Then as I started finding shims with wear patterns on them and sometimes no numbers (remember to put number side down in the bucket) I would use a digital caliper and arrive at the right shim to swap it with.

Cool.
Buddha.

I was there at 0.0 clearance on both intakes last month, it's hard to guess at the correct shim when 0.0 clearance could mean the valve is fully closed with no slack at all, or it could mean the valve is being held wide open. I stuck with the method of measuring when the cam is facing forward or away positions as per the FSM.

For a second opinion, I swapped in an exhaust shim into the intakes, and used that data to guess that I needed a 270 (2 steps smaller shim) on both intakes. I bought one and tried it in both intakes then bought another just like it. That worked out well with .004 inches (sorry to mix measurement standards) of clearance on the intakes when I was done. I left the exhausts at 10 thousandths clearance, a bit loose but they'll tighten up over time, and as Buddha said, it may be noisy but it won't hurt it.

The end result was my compression went up between 10 and 15PSI on each cylinder, so I was definitely "tight" on the intakes. I balanced the carbs as well, they weren't far off. The bike was remarkably stronger, able to pull and accelerate in 6th gear up a steep hill with a pillion rider, that was not possible before, so a genuine metric beyond just seat-of-the-pants feel.

I can't explain your measurements at other positions, but I did get consistent measurements sticking with the FSM method, with the caveat of turning a few cycles to get rid of excess oil, as Buddha mentioned. I suggest just picking that method and sticking with it.

With your mileage I'd guess it's unlikely you'd have to jump all the way to the minimum shim.