From our Search on this board.
Remove right inner pocket and radiator cap.
Bike should be on the side stand during the draining.
Remove the drain bolt (on water pump - left side of engine forward of the drive belt case).
Remove reserve tank cap and drain reserve tank.
Reinstall drain bolt with new sealing washer.
Place scoot on center stand - level ground and all that.
Fill the reserve tank to the upper level line.
Fill the system with recommended coolant up to the filler neck.
Bleed air from the system by doing the following:
Start engine and let it idle for 2 - 3 minutes.
Crack open the throttle 3 to 4 times.
Stop the engine and add coolant to the system to the proper level.
Reinstall radiator cap.
Check the coolant level in the reserve tank and add if necessary.