Do you need engine cooling fans in winter?

Clearly your Harley’s engine will run cooler in winter than it does in summer, but not as cool as you may think. Most Harley Davidson models run air-cooled engines; cooler air means a cooler engine, all other things being equal.

But the amount of cooling depends on the difference between engine temperature and air temperature (remember that from high school science?)

Some calculations:
Summer: head temp 180°C, air temp 40°C: difference = 140°C.
Winter: head temp 180°C, air temp 20°C: difference = 160°C.

So the cooling effect in winter is only 4-5% better (calculated using the Kelvin temperature scale).

Riders feel a big difference between summer and winter, but your engine won’t. I’ve been using my cooling fans in Sydney traffic even in these cooler months.