Alright, a while back I was postulating on the VTR's cooling system, coolant temperatures and airflow through the radiator. It's been pretty hot in Chicago-land, so far, this Summer. While July wasn't the hottest on record, it was pretty close. I've seen more 100º F days this year than I've seen since I've lived in the area (~20 years). The VTR continues to handle the heat with aplomb, it's me that worries about it.
I did check the system from a very basic stand point; the radiator is free of external debris that might be clogging the fins (and preventing airflow), if I ground the wire that runs from the fan to the thermo-switch, the fan does run (so the fan motor is OK), the radiator is properly grounded (so that when the switch does activate, the fan should come on) and the switch measures close to infinite ohms (resistance) when cold (as it should). What I have not tested is if the switch itself does work. This would require it being removed from the radiator and heated in a liquid until either it activates (resistance goes to zero) or the liquid reaches a temperature beyond the point where it should activate (which would indicate a failed switch). Obviously, I'll wait until riding season is over since I don't seem to have an issue, right now.
Additionally, we're dealing with a ~23 year old radiator. It's possible that it needs an internal flush to ensure that all of the cooling tubes are clear and functional. It's also possible that the coolant is way beyond its service life and is no longer efficiently conducting heat. Lastly, the thermostat could used to be replaced, if it's original equipment (which I suspect it is).
Again, due to the fact that the cooling system seems to be doing it's job, all of this can wait for Winter.