Classic Motorcycle plates are the successors to E/A motorcycle plates. Their issuance started on April 1, 2014.
These plates are issued to motorcycles at least 20 years old. Numbering is similar to the Classic Vehicle plates, but with one less digit/character at each end: 0-ABC for Classic Motorcycle vs. 00-ABCD for Classic Vehicle.
See also Early American Motorcycle.
These plates started in the zero (0-) series.
Working through the letter series.