You can now find a collection of service bulletins for the Sedan and Coupe
on my webpage. These were issued by Honda "as needed" to bring to light
various issues and problems that became known as time went on. These were
issued between 1970 and 1973.
You may find that some of the recommendations offered here were never done
on your 600. Take a look - you may be 30 years late!
Steve
http://www.honda600coupe.com/Manuals,_b ... ments.html