If you're running a Jap bike that's maybe a few years old (mine is '70s), this site in the Netherlands could be of interest.
http://www.cmsnl.com/The website leads you through a huge selection of bikes, and then lets you open up an exploded diagram (as per the fiche that the dealers used to use), along with parts numbers, plus cost and availability through the site - very useful.
I haven’t done any purchases yet, so can’t comment on the company, but have used the site to cross reference part numbers of a particular model on a year by year basis, which can help if you’re using e-bay to source something that’s from a different year.bikes