I'm having some problems setting mine up too...just cleaned both carbs and changed all o-rings etc, including the one on the butterfly shaft on my right hand Bing ..I suspect that I may have left too large an opening when reseating the butterfly, but I was playing around for ages getting it to seat in the position that seemed best (least light visible when pointed towards the light)

the bike runs perfectly well off idle, however the annoying thing is that I just can't get it to idle smoothly. I can screw both mixture screws right in (more so on the right side), and the bike will just start to surge like crazy. I've sprayed brake cleaner all around, with the engine running and it doesn't seem to have any obvious leaks. There's no dying point at all, and I've settled for a slightly high idle, unscrewing the throttle stop screws until they're barely toughing the cable stops.

It runs ok with both screws 1 turn and 1 1/2 turns out, there's good engine braking , and I'm just going to leave it that way...but that surging when I screw in just bothers me...isn't it supposed to kill the engine when I do that?

And yes, I can confirm to the OP that the mixture screw is actually a Fuel screw, unscrewing = richer idle mixture
Sorry for the hijack. Thanks for any hints. the bike is an r 80 G/S by the way....!