Yamaha YFM660R Owner's Manual page 302

NOTE:
_
G
If water is added, have a Yamaha dealer
check the antifreeze content of the coolant as
soon as possible.
G
The radiator fan operation is completely auto-
matic. It is switched on or off according to the
coolant temperature in the radiator.
_
If your ATV overheats, see page 8-130 for details.
8-37