Had this same issue. You can find Plastic epoxy at home depot or advance auto parts, Use it on the back of the piece then you can sand the front and paint it. You couldn't tell as long as you are using actual paint, not rattle cans.
If you need a paint match I suggest color rite. Color Rite Distributing Co.
It matched my 2001 ZX-12R perfectly when I needed it.
EDIT - Mine cracked right at the top of the nose fairing where the mirrors and fairing out to the front "antler" bracket. That area has a lot of stress and after using the epoxy it never showed signs of weekness and I wheelied that bike all the time.
If you need a paint match I suggest color rite. Color Rite Distributing Co.
It matched my 2001 ZX-12R perfectly when I needed it.
EDIT - Mine cracked right at the top of the nose fairing where the mirrors and fairing out to the front "antler" bracket. That area has a lot of stress and after using the epoxy it never showed signs of weekness and I wheelied that bike all the time.