for a possible sticky:
A list of links for online microfiche for various manufacturer's OEM (original equipment manufacturer) parts catalog. These have "exploded parts diagrams" for the various bike systems and show part numbers:
Bike Bandit (BMW, HD, Honda, Kawasaki, KTM, Suzuki, Truimph, Yamaha, others)
Ron Ayers (Honda, Suzuki, Kawasaki, Yamaha)
MR Cycle (Honda, Kawasaki, Suzuki, Yamaha)
D&S Cycle (Honda, Kawasaki)
...others...
Note: You don't see real micro-fiche (pronounced "fish") much anymore but they used to be page-sized transparent images that were used mainly by auto-parts houses and dealers for locating model-year parts. Each "fiche" contained hundreds of pages of small images that had to be magnified to view. There was a "micro-fiche" viewer that allowed you to index (row-column) the proper page and view it. This is all done electronically now.
Microform
That's a start...