I don't like for someone to start trying to negotiate the price before they've even put forth the effort to come look at what I have for sale (vehicle wise). If it's something that's not going to be paid for in advance and shipped the time to talk money is face to face. And it's much easier to turn down an offer over the phone or in an email than it is when the money is in front, nothing says I'm serious about buying more than $100 bills.
If you have any reservations about the bike being too big I would say pass on it.