I just swapped a perfect running motor into a bike that had a blown motor, now I cant keep it from overheating after about 25 minutes ride time. I flushed twice, new oil and filter, thermostat good, water pump good. Only difference after swap is the fan wouldn't kick on after hearing up so I hard wired it with a switch. I burped it numerous times until I saw no more air bubbles. After the bike gets hot and the temp gauge flashes "HIGH" the overflow reservoir isn't even boiling.