TexasKZ wrote: Kawasaki ran two of the thick single discs in the very early Z1, but changed to thinner ones. I suspect it had in part to do with rotating mass and unsprung weight. The extra rotating mass would partially offset the effectiveness of having two brakes, and thinner ones cool more quickly.
More unsprung weight is not what an already too soft suspension really needs.
I agree with the supposition that more unsprung weight may have been an issue, but I think in the overall scheme of things it really didn't make much difference in normal street application. For the life of me I don't understand why Kawasaki didn't equip all the KZ's and Z's with dual disc front brakes except as a way of saving some money on the back end. Of course perhaps they were ahead of time by offering an optional dual disc brake accessory kit in order to make more money after the sale. Something that H-D has gotten real good at. Simply stated, take off parts that you can and ones people like and make them available in the accessory catalog.
Rick H.