Help What makes a bike run hot?

An engine that is run as hot as practicle (without doing engine damage) will be a more efficient engine as it will burn all the fuel in the combustion chamber and make the most of it's energy.
I would suggest that you rig up some sort of tempory temp gauge to get an actual measurement of the water temp and if it is not above about 95C when riding then I would leave it alone. Possibly use an old radiator cap with a sender unit soldered into it running to a gauge taped to the bars, or similar. You may be able to find a sender unit from a car that will fit into where the fan temp switch is on the radiator (item 27010 on the above picture). This will give you an idea of what the actual numbers are, not just going by the heat coming from the engine.

 

Yep, I have the same issue. My Green ZXR is the only one that runs hot. My other ZXR's rarely heat up for the fan to come on.

 

But are they really running hot or is the fan switch just set high?
Need to know the numbers rather than just saying it's hot cause the fan came on.

 

These are good i have one
http://www.ebay.com.au/itm/37mm-Smo...684374?hash=item5696d45196:g:B1MAAOSw32lYz592

 

I posted that water temp gauge as another option to the one you posted.
These gauge's are cheap, small and are easier to mount than the one you posted
You need another water temp gauge to see if your bike is running hot or at the normal operating temp
Like @Murdo said it may have the wrong thermo fan switch fitted and it's coming on too late, or might have the wrong temp gauge sender fitted and it's showing it's hot but it's actually running at normal operating temp
If the water temp is up then the oil temp is up too.

 

Any one of those will work as a tempory set up to get an idea of the actual temp.

 

I can ride all around town without the fan coming on, but when I leave the bike running while I open the gate to get into the yard it comes on. Engine is not hot, just fan doing its job.