Robert M. Pirsig rode a 1964 Honda Superhawk CB77 during the trip that led to his popular book Zen and the Art of Motorcycle Maintenance.
Although the author's bike is referred to often in the book, the make or model is not noted. However, it can be seen in the photo of the author and his son, on the following link, that was taken during the actual 1968 motorcycle trip the book is based on:
http://ww2.usca.edu/ResearchProjects/ProfessorGurr/gallery/Pictures-Robert-Pirsigs-original-1968-trip/aam
The book does refer to his friend's bike, a BMW R60.