I flush mine every other winter. I just drain my rad, fill with water and run the bike till it's warm. Then I drain the water and refill with fresh coolant. For coolant I go to the Honda car dealer and buy their silicate free Honda coolant (Blue). One gallon at the car dealer is about the same price as a quart at the motorcycle dealer.
Just a drain and refill every 5 yrs. If the old AF looks contaminated or weak I would flush, otherwise if no current problems you are now chasing, just replace. You can rock bike left/right to get every last bit out.
Prestone silicate free available everywhere and a jug of distilled water from grocery store. I mix mine 60/40 water just because.