2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 172Get this manual
COOLING SYSTEM Fill the reserve tank to the upper level line and install the tank capInstall the right front fender ('04'05: page 3-6, After '05: page 3-6)
THERMOSTAT
REMOVAL
Drain the coolant from the system (page 9-7)Remove the three bolts and thermostat cover
Remove the thermostat from the cylinder head
INSPECTION