Place a garden hose into the radiator for a couple minutes with the drain plug open if you can, and ignore the front drain bolts. The only bike in my collection i have licensed, insured, registered, inspected and on the road so far this season is my '89 NT650 Hawk GT. My first bike was a tiny 1966 2-stroke 125 cc in 1988.
Good luck with your bike; keep the revs down and keep the cooling system fresh and clean. Got tools ??