Here are two part number finders useful for most Japanese VMXers.
Partzilla is good for finding the part you need when you can work straight from the microfiche, that is you are absolutely sure you know the part you need. It is also very good for cross referencing parts for multifit purposes.
But some times the microfiche images for old bikes just dont cut the mustard. In these situations it pays to use CMS Spares. Their microfhiche are useful as for each partnumber is a photo of the spare - just to be sure!