[eon]

I’ve never owned the Ninja but I’m pretty certain it could cruise at 70-80 all day long. I own a big heavy maxi scoot with a lower power to weight ratio than the ninja and I can (and have) cruised all day long at those speeds (admittedly mine is 500cc but I’m not sure that is significant).

Hmm, there is BMWs F650GS & G650GS. The link below may give you some ideas.
http://www.oldguy.us/easy-riding/bg-models-standards.php