Batman & Robin
Looks like a six cylinder bike. Did anyone but Honda make such bikes? Probablement une Goldwing modifiée.
Honda 1500 F6C. http://www.bikez.com/bike/19997/index.jpg (Maintenant, il existe peut-être une version noire, du style de ce qui s'est fait avec les Yamaha Midnight Special...)
The name 'Robin's Batbike' is my invention. I don't know what it was named in the film or the comics. Its just to give you an idea what that is. About the make I can only tell that in the end-credits they thanked Honda.
Guess: Honda Shadow VLX http://www.geocities.com/jdutta78/images/vlx/shadow.jpg Many parts are change for to change the impression of appearance. (Chrome parts at the cylinder side, air cleaner cover, seat, welded down tube and rough mesh on the flame, rear suspension height is lowered...) I checked the Honda motorcycle of these years that can use as base model. As a result Shadow VLX seems most likely from the frame & tank shape.