The Suzuki manual says after draining the old coolant through the water-pump outlet hose, reconnect the hose, remove the radiator cap (it's under the gas tank), put the bike on the centerstand, and pour in coolant up to the level of the thermostat connector inlet. Now rock the bike slowly side to side to release air trapped in the cooling system; pour in more coolant to the level of the thermostat inlet. Start the engine, topping off the coolant as the level drops, until no more air comes out. Put the radiator cap back. After warming up and cooling down the engine a few times, add coolant to the specified level on the reservoir bottle.