air v's water cooled

[Simon.Pieman]

The main reasons for the motorcycle manufacturers using water cooled engines was to quieten the mechanical noise down to pass noise regs and because the new 'fashion' to enclose bikes in fairings required a need for better cooling (the engine sees less airflow enclosed by a fairing of course) The GPz900R is a good example of this, although they didn't really get it quite right and it did tend to overheat rather a lot.
Manufacturers would love to make more aircooled bikes because they are cheaper to produce.