Boxerworks.com

Bob Gauer did mine. You can find his phone # by Googling his name & "BMW", or you can PM him here - "robert" and see if he is still doing them. If he is, I heartily recommend him.

Are they upgrading the seats on the '81 and newer bikes, or just replacing valves?

Randy Long installed all guides, upgraded exhaust valve seats, and all new valves, checked valve spring load vs deflection
when he did mine.

Most the reputable guys will replace the seats for you. If I wasn't going to have the seats replaced, I'd have done the job myself.

Bob Gauer told me last year he only does some local people/friends work now and isn't taking on other work.

I went to Randy Long.

He does use, has used very extensively, Black Diamond valves and the correct guides for them.

His work is great, whether you can believe him vs. the anti-Black Diamond folks is up to you.

Put a few thousand miles on them so far. Working well.