This is a joke, right? Sarcasm is very difficult in print you have to give me a clue that your not joking.
I most certainly am not joking; Many of us older
motorcyclists feel quite strongly about the term, associating it with a certain variety of two wheel user, often the more anti social types, [but don't get sucked into the argument biker v. motorcyclist row here]
It was not a term used in the era you are using.
A girl [or a bloke] used to a Bantam would certainly be in deep merde in the circumstances you describe, If you are trying to get across some early, or learner ability on the part of the girl, I suggest you look at the idea of her previous experience being on a small 250 such as a BSA C12, which was a big little bike; staring procedure would be much the same except for the valve lifter control which a lot of newcomers to big single machines still have trouble using,its quite a knack.
You may need to cough up more info re the Bantam years of this girl.
whats so scary about facists? [joke alert]
[ For what its worth I am also an author]