First time working on the GS engine but I have checked my engines valve clearances with the following results: both intakes were 0.06mm, the left hand exhaust is also 0.06 and the right exhaust clearance would take a 0.15 feeler guage. The first three all are in spec, so I am not proposing to do anything about them but a search of the archives shows that the general GS consensus is that it is fine for exhaust valves to be run looser than spec, so my question is whether I am better off putting a larger shim into the LE side? My feeling is that it could be tightened up a bit but it seems to run fine now so I just wanted to check. TIA!

.15 is the absolute largest I would run. Depends on how hard you run your bike. If you don't spend much time at the top half of the rpm range you could leave it as is.  If it was my bike I would probably swap the shim to get it down to .10.

Brilliant, thank you Bluesmudge. The bike runs fine at the moment but it does rattle a bit. I'll organise a new shim and hopefully that will help.

I had no real issues getting the old shim out but the new one is proving difficult to fit correctly. I think that one issue might be the amount of oil,so I will try to remove that tomorrow but are there any tips that make this part of the job easier. The old one kept on slipping back into position until I managed to remove it so I thought that this would be easy too....

That's weird. I've never had an issue getting the shim in. It usually just slips right in. Are you sure its the correct diameter shim and the engine didn't rotate so that the cam is blocking it? You should leave the shim removal tool in place too to make it easier to get the new one in.

I must admit that I didn't measure it with the calipers but it looked the correct size when placed on top of the old one. My thought is that there is too much oil pooled on the lower (front) part of the bucket (if that's the correct term) and this is stopping the shim from siting properly. I will try again in daylight and see if i can wipe away some of the oil. I have not rotated the engine after removing the old shim and the valve tool has remained in place as i waited for the new shim to arrive so there should be no mechanical reasons for the shim not to fit if it's the correct diameter. I will keep my fingers crossed and try again...

The most trouble I ever have is having the shim slip off the bucket and halfway fall off the bucket but its as simple as moving back up onto its seat in the bucket with a pair of tweezers. It should just kind drop/click into place on the top of the bucket. If you have a lot of oil there on top of the bucket you could absorb it with a clean towel but even with oil you should be able to just press the shim into place and it will displace the oil.

Sorry for not getting back on this -the issue was the amount of oil and me not using enough force to displace it. I used a bit of towel to soak up some oil then lined up the shim and pushed it into place, which caused the excess oil to be pushed out of the groove. Job done! Thank you for all your help and support!