This is interesting.
In my search to find what KZ's had what size fork uppers, I discovered this old Cycle World Magazine article which discusses the KZ750 / 4 and compares it to the KZ650.
it says "The last 650 tested had a quarter mile time of 13.40 at 96.87 MPH..."
It is neat to read through old magazines via google books. I remember riding my bike to the local bike shop and buying this magazine when some of these issues were being published. :laugh:
If you're feeling nostalgic or wanna search up some history on the KZ650 or KZ750/4, try this
[ Google Books / Cycle World Mag ]
.