Make sure you didn't dislodge the radiator cap from the radiator neck. I have a buddy with a zx-9 that this happened to but don't know if the twelve would have the same vulnerability due to location inside plastics. It's likely to be something like that, not holding pressure in the system. Good luck.
Keeping the "Hap" in "Happy Holidays"!
Regime change begins at home.
Blind patriotism is worse than no patriotism.