Well, Sixto is right about no periodic adjusting while running, but I have seen a procedure in the CD Rom manual, with a go/no go gauge used to set the height. I believe the shims under the rocker arm above the valve are used to properly set them.
Send me an e mail, and I can send you the *.pdf file from the manual. Should be in my manual, I think it goes from 81 to 91.
1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)