Honda TRX680FA Owner's Manual page 166

Coolant
3. Remove the steering cover ( ) and reserve tank cap ( ).
Always add coolant to the reserve tank. Do not attempt to add coolant
by removing the radiator cap.
4. Add coolant to the reserve tank as required to bring the coolant level
to the UPPER level mark.
FRONT
(4)
(4) steering cover
5. After adding coolant, install the reserve tank cap and steering cover.
Servicing Your Honda
158
4
(5) reserve tank cap
5
(5)