I have 17k miles on my 2005 and have never checked or adjusted valves on any bike of mine in 40 yrs of riding.  I'm getting an education now as there is a lot of beneficial experience shared on this and other forums. 

I have occasional backfiring when cold and my idle is really wacky after ultrasonically cleaning the carbs.  I knew my valves had to be out of spec so I check them and found zero gap on every one.  All the buckets turn.  I swapped an existing smaller shim into its new position and attempted to confirm the right gap before ordering the rest of the shims.  I'm still getting zero gap.   I went down 5 with one and then went down 10 with my smallest shim and still no gap.  I suspect the oil layer under the bucket is keeping me from showing what the true stack-up is now.  I know I can't turn the crank/cam with shims out but I suspect this is what I need to do to force more oil out.  How does everyone else that doesn't have a whole kit of shims do this?  Should I just order -.05 or -.10 on all the positions and a 230 for gauging and cross my fingers?

Maybe you have already and I'm just not following but when you put a new shim in, you have to rotate the engine several times before you re check the clearance. Also, if your smallest gauge doesn't fit, but you can still rotate the shim (not the bucket) the clearance is >0. Thus a 5mm thinner shim should put you in spec (depending on what size gauge you're using). If you can't rotate the shim (clearance really is 0) it will have to be a trial and error thing unless you get a much thinner shim to gauge as you suggested. Although, I would be very surprised if your more than 10mm out of spec.

Interesting.  Made the 1st shim change on my 97 at about 40k miles and the 1st on my 02 at about 31k miles.  Bought only 6 or 7 shims in the 80k miles I ran the 97 and used the same 6 or 7 to go 100k miles on my 02 GS.  I'd never consider a shim kit.

On my 97 one exhaust valve set at a minimum clearance required constant changes and was down to a min 215 shim at 80k miles.  When my 02 started the same pattern I went to a wider .003-.005" setting for exhaust valves and was only down to a 245 smallest shim at 100k miles.  My intakes never required any shim changes.

If all your valves are too  tight to measure and you can turn the bucket with your finger I'd get the 2 size smaller shims and go from there. You need to turn crank a turn or two to squeeze out oil after shim change before rechecking.

http://img.photobucket.com/albums/v443/jcp8832/GSvalvelogs_zpscvcef42y.jpg

Are you certain  the cams are in the correct position? I like to use step feelers, as they provide a thin lead-in for tight clearances.

If the buckets are turnable or you have good compression... then they are not below zero clearance.  Below zero valves will affect compression and/or allow exhausts to burn.

Dry the shims and inside of buckets of excess oil, or thin with a bit of solvent.   Then shims in, plugs out and turn over engine (to seat shims) , follow valve clearance setup procedure in manual.  Intakes shouldn't really have changed much 5-10 maybe, the exhaust are the ones that can tighten up below zero, I like to run loose .13-.15 mm. 

if things are tight then I dont think there is much choice but to get at least one  single much smaller shim (25-40) and start from there with an initial measure on all four valves, then take your shim collection an trade with bike shop service dept, its usually 3-4 $ a trade instead of 10$ for new.  Trouble is they may have used all the ones you want