Harley-Davidson Parts Catalogs These parts catalogs contain illustrations of every section of the motorcycle, breaking them down to the last nut and bolt. Each part, even the tiniest washer, is referenced to its name and part number. In some cases, the part listing includes dimensions (especially with nuts and bolts), and the years it was used on that model. For anyone contemplating the restoration of a motorcycle, a parts catalog is not optional; it is a reference you cannot do without. Only with a parts catalog can you correctly identify and acquire missing or worn out components and hardware.