2007 Kawasaki Ninja 250r Cooling Problems

i live in the great state of Florida, recently i saw that my bike was getting really hot at stop and go on the streets. getting close to the red zone. I emptied the coolant out which has been there since the start 3500 miles in. and put 50/50 Preston coolant in. I still am having the same issues, now i am thinking about going to 100% water and Hyper Lube Super coolant mix, any suggestions?

Also anyone know the capacity of my radiator? i cant find my manual