The main differences between the two models naked styling in the vein of the larger Z800 and Z1000, and the wide, flat handlebar that gives the Z650 a more upright riding posture. Without the full fairing, the Z650 weighs about 13 pounds less than the Ninja, with Kawasaki claiming a curb weight of 412 pounds for the Z (or 408 pounds without ABS).
As for U.S. availability, Kawasaki didn’t officially confirm it, though buried in the press information is the Z650’s helmet lock will be available as an optional accessory… in the U.S.A. While its predecessor, the ER-6n, hasn’t been in Kawasaki’s U.S. catalog since 2010, it looks like we’ll be seeing the Z650 in American showrooms – unless things change (remember the asterisk!)