Honda PA Manuals
This manual is for a 1983 Honda PA50 II, but it applied to all models from 1978-1983
Or go to your favorite on-line Honda Dealer. They have "Parts Finder" tools that allow you to find Honda part numbers. This is a good tool to verify if another year's part will fit your Hobbit.
A 1983 Owner's Manual can be found here: http://www.mopedriders.org/article_view.php?faq=2&fldAuto=26