Greetings,
ORIGINAL: flywilly
Conversely, MK catalogs list 20, 40, 60 and 4C sizes for both the Magic and Aurora; though I'm not sure what differentiates the 60 size from the 4C size (dimensionally they are the same).
Don't know about the Magic, but in the case of the Aurora, the basic difference between the Aurora 60 and the Aurora 90 was that, in the 90 version, the firewall was moved rearwards to fit a 90 size four stroke motor instead of a 60 size two stroke.
Best regards,
George