$900. That's what my cylinder head repair cost.
 

This is a cautionary tale.
Last time I set my valves was at 63,000 miles, about 19,000 miles ago. The intake valves for cylinders #2+3 were all hard to check, I could get the right feeling guage in there but it took alot of effort, really had to force it in there. As all the other valves were well within spec and wearing almost exactly evenly, combined with my inexperience with feeler gauges, I summed it up with I didn't know what I was doing perfectly and all was good in the world, I might have dropped one shim size on them I don't remember.

Recently my bike did not want to idle when it was warming up, and sometimes after a long ride too but that was very rare. Still ran great, power was fine etc. I did notice loss of gas mileage though as well. When I blew a fork seal I said F it and decided to clean throttle bodies, check valves again etc while everything was apart. It turns out, with no shims installed at all, I now have .010-.011" clearance for those 4 intake valves. FML. I sent the head to Evan Steel Performance. They said all intake valves were bad, only a [short] matter of time before the others lost adjustment too. So new intake valves, new valve stem seals for all 16 valves, and all 32 locks with a valve job is whats happening now. Between that, coolant, some hoses, fork seals, bushings, sliders and oil, plus the front brake pads [found them almost at metal when I pulled forks, oops] I'm spending almost what a used 600RR cost, and that's with me doing all the work! I'm fairly sure if I hadn't left those valves so tight I wouldn't be having this problem right now. So if you aren't sure, get a second opinion!!!

This is what I'm afraid of... I have done valve adjustments couple times but I'm never 100% sure if I'm doing it right, I think it takes a fine hand to tell how "rough" the feeler gauge should be... I've been thinking of getting them done at the shop the next time it's due but they charge $600-700 to do it here. Hmm....

Anyway, glad you got it sorted out. even if it took some moolah to do so !

if it took a lot of effort, then you ended up compressing the spring to get the gauge in there. the gauge should slide in with relative ease but still resist a little bit. kind of hard to explain, you just have to get a feel for it.

dont be too afraid to do it yourself, if you're unsure then keep them on the loose side to be safe.

also helps, when you think you have the right feeler gauge, to slide the next smallest and next largest feeler gauge in there until you 'get a feel for it'. smaller should slide right in, larger should need some force.

if you always go back and re-check with different gauges you'll be in good shape. bikes like this are extra difficult due to the angles you're working with, and the difficulty in checking/rechecking your measurements once you've changed a shim.

don't forget that sometimes when you start measuring, the bucket might not be entirely seated on the valve either. turning the engine over slowly by hand a few times first might help with that.

this is something that should be done with no time pressure on a weekend or something

but 19,000 miles between valve checks is well beyond the recommended service interval, in this case maybe if you re-checked them earlier it might have saved it (or maybe the head was already in rough shape just due to high mileage)

Yep, the first time I did it I spent hours checking and re-checking w/ feeler gauge of a size, the next size up/down, re-handcrank engine to double check, etc lol. I'd like to think I got the "feel" of it, but as I have never had any actual hands on training it is easy to doubt myself.

What really tripped me out was that sometimes for a certain valve I'd think I found the right size (say, 0.17, just arbitrary number) because it would slide in with a good-feeling amount of "roughness" and .15 was way too easy to slide in and .19 was too jam-y. But then I'd try sticking in 0.13+0.04 and it would be way too easy to slide in. Dunno if my feeler gauges are crap or it's just like that or what. I just adjusted on the looser side if I really wasn't sure and hope for the best !

I've learned feeler gauges much better since my last valve setting, hence why I figured out my problem so quickly this time. I'm not worried about my interval [normally 32,000 miles] as all other valves are well within spec each time I've checked, it was just these 4 that got me confused in the beginning. Live and learn.