I bought my 07 with half a tank in the overflow. It slowly decreased until there was nothing in it. Probably from tip-overs. [COLOR="Red"](or [/COLOR][COLOR="Red"]evaporation)[/COLOR] [COLOR="Red"](the catch can is open to the atmosphere)[/COLOR]But my radiator has always remained full, without adding. I can hear fluid transferring as it cools. [COLOR="Red"](is the catch can still empty)[/COLOR]A couple ounces wouldn't hurt, but still check it at the rad cap. I like watching the steam pour out of the CRFs at the races...[COLOR="Red"](I think all bikes do this when the pressure in the closed system exceeds the pressure required to lift the cap seal off it's seat thus reducing the pressure in the system allowing the coolant to boil, rapidly evaporate, and then condense in the atmosphere.[/COLOR]
If you run a catch can, your bike does this too. The only difference is this is all happening inside the concealed environment of the catch can.