I used to have a KLR650, and later a 250 Ninja. I don't ever remember hearing the radiator fan run while I was riding or stopped at a light, but then I do wear earplugs while riding. When I parked the bikes in my garage it was pretty usual to hear the fans for a couple or three minutes after shutdown, even with the ignition switch turned OFF. I do not use the kill switch, other than to test it very infrequently. Every so often I will hear the gas tank vent as heat rises off the hot engine, too.