Is that verbatim? Or a simple mistake on your part? Because note (and it is easy to miss due to the commonalty of the more recognizable term) that mine are stamped MOTO(no R)CYCLES. EDIT: I haven't researched it yet, but if they're legit, and I have no reason to think they're not, I suspect it was an early term in the nascent days of the industry.
I've got one of those. Maybe the "moto" spelling was used by more than one manufacturer, but I think Indian, at least, used it intentionally. "Moto" refers to the the fun, liberating, rapid
movement of the vehicle, rather than the (loud, smelly, tempermental) engine that accomplishes it.
Con moto is a direction for music tempo.
I ran into the spelling a couple years ago when I found a Vacuum Grip valve cover pliers.
Edit: (thanks to DadsTools for provoking the research)
Hendee produced motorcycles beginning in 1901, but changed their name to
Indian Motocycle Manufacturing Company in the 1928, and went bankrupt in 1953, though (according to Wikipedia) there were several attempts to revitalize the brand before the current Polaris iteration. I would guess that the "Motocycle" spelling probably ended with the first bankruptcy.