Is this normal, or even possible. Last time I check about 8,000 kms ago the intake valves were .06 and the exhaust were .05 now all the clearances are .06.

I've only heard of valves getting tighter.

Not a large diff here, probably due to measurement.

You're talking ten thousandths of an inch and that's something like the combined thickness of two strands of human hair.  It could easily be from some carbon fouling on the valve seat.  If you check it tomorrow it might be .050 again.
Or inversely your .050 measurement was from some debris on the feeler gauge or on the shim...


From where you are I wouldn't worry about a .010 variance: at either measurement you have +/- .020-.030 tolerance left to go before you hit the edge of specification.


If there's anything I've learned from being a machinist it's that perfect is cool but in tolerance is in tolerance, so it's good to go.
There's also some days where I'll measure a part at 2.255 and maybe Dave will measure it with the same calipers at 2.253.  Or later in the day I'll get 2.254.  For as precise as we can make things, we're still human, and there will always be variance and margin of error.

My valves mostly got looser. I went form 250 - 275 in 1, 260-270 in other etc etc over 48k miles.
There was a crows foot type scratch in 1 cam lobe, that also got fainter as it wore.
Valve Stem tops, buckets and the shims themselves etc also wear. That wear makes it loose.
Of course the seats wear and make it tight.

Cool.
Buddha.

OK, thanks, that is exactly what I was wondering. So if valves are not getting tighter, can I presume that to mean that they are not being damaged from the engine running a bit lean. You see my GS is running a bit lean, but it's not getting hot and it runs well, I was thinking of enriching it mainly to stave off any valve seat damage caused by excessive exhaust gas heat. Does the valves not wearing imply that the rich mix is not causing any problems?

Quote from: The Buddha on March 12, 2017, 05:23:18 AM
My valves mostly got looser. I went form 250 - 275 in 1, 260-270 in other etc etc over 48k miles.
There was a crows foot type scratch in 1 cam lobe, that also got fainter as it wore.
Valve Stem tops, buckets and the shims themselves etc also wear. That wear makes it loose.
Of course the seats wear and make it tight.

Cool.
Buddha.

Checked my GS500 valves regularly for 180,000 miles on my 97 and 02 GSs and never changed a shim on the intake valves while the gaps varied up and down about .001" (.0254mm) and never gave that a thought.    

The exhaust valves set at the .001-.003" Suzuki spec began requiring shim changes at about 30k miles and the one that initially ran with only a min .001" clearance on the 97 was down to a min 215 shim by 80k miles.  On the 02 GS I went to a wider .003-.005" setting spec and the smallest shim at 100k miles was a 245.  The wider gap allows for a longer cooling time of the valve on the seat. 

@gsjack.

Thanks, I'm on about 20k miles atm, will widen the exhaust clearance to 4 thou next head time I have the the cover off in about 4k miles.

Looser is better, but the racket it makes would prevent me from detecting subtle changes in other noises and hence I ran them closer to the tighter end of the spec. I made it barely 30k before the thing was using more oil than gasoline.

I've heard if the bike ever ran hot, past 250F oil temp it would always use oil till it was rebuilt. No idea, but that bike was used and abused a good bit before I picked it up, and I cluelessly ham fisted a lot of crap on it in the first 4-5 yrs of owning it, then I cluefully ham fisted it.

Cool.
Buddha.