I'm doing my first valve clearance job and my exhaust valves (with 2.50mm shims) are tighter than my smallest feeler gauge (0.04mm). BUT, I can turn the buckets by hand. (I wouldn't say they are easy to turn, but I can do it with my finger.) What's the rule of thumb on the clearances here? If I can turn the buckets, I assume there is some clearance so call it 0.01mm? I'm need to order shims and would ideally like to get it right on the first try. Thanks!

If it was me I would estimate it is zero clearance and buy shims accordingly. 0.001-2 "too much" valve clearance is not a bad thing, but you'll kick yourself if you get shims that are too big and wind up replacing them and still can't get your feeler gauge in.

I had zero clearance on mine and had to drop 0.15 on one and 0.1 on two and 0.05 on a third, so wasn't all that predictable.

Its expensive and dismal having them in an unknown state - If you are in the UK I can post/lend you a 2.40 to use as a sizing guide if you want? I ended up buying it to work out the gaps on mine (down from ~2.6x to ~2.50)

Thanks for the offer, but I live in the US. I ordered my best guess for the valve shims and an extra 2.15mm shim that I can use as a test if the new ones don't work. Hopefully, if I set my exhaust valves loose (as per the recommendations on here) they won't move around for a while.

On a related note: Is needing 2.40mm shims on the exhaust valves typical for a GS500E with 31,000 miles (50k km)?

postage might have made that uneconomical

my bike on 43k miles has

IN left 2.55 (0.07 gap) & right 2.50 (0.06 gap)
EX left 2.55 (0.06) & right 2.50 (0.05)

I very mildly lapped my valves in when i redid the head so that would account for a little additional wear. One of the shims that came out was marked and measured 2.68 which suggests the factory might have not been hugely accurate if they had to have off-sized shims.

nit, remember that the clearances will change a little when the motor heats up.
You check them cold of course.