ZXR250c running cold...

Hey guys,
I have owned my zxr250c for about a year now and it has always run cold. It sits just above cold normally, in traffic it rises and the thermo fan kicks in as normal, however as soon as i get back up to speed it comes back down to just above cold again.
I would just like to get peoples opinions is this normal for my bike? I have read that other people have experienced this, or should i go about replacing the thermostat?
Will running cold cause premature engine wear?
Just curious thought i would ask the people in the know. I was thinking about changing my coolant as its a little brown and figured there isnt any point changing the coolant then fixing the thermostat and having to do the coolant again!
thanks for any advice
Pete
I have owned my zxr250c for about a year now and it has always run cold. It sits just above cold normally, in traffic it rises and the thermo fan kicks in as normal, however as soon as i get back up to speed it comes back down to just above cold again.
I would just like to get peoples opinions is this normal for my bike? I have read that other people have experienced this, or should i go about replacing the thermostat?
Will running cold cause premature engine wear?
Just curious thought i would ask the people in the know. I was thinking about changing my coolant as its a little brown and figured there isnt any point changing the coolant then fixing the thermostat and having to do the coolant again!
thanks for any advice
Pete