In this case, in 2010, Harley -Davidson patented a system to prevent its air-cool engines from running too hot and creating a risk of exhaust-valve seat distortion and even head cracking.
A possible remedy investigated by Harley-Davidson would be to “wrap” the exhaust valve seat with a hidden liquid cooling passage running water. Why water and not oil? Because water cools better than oil.
The system would be made of small radiators and an electric water pump. Of course, getting a patent doesn’t mean that Harley-Davidson will exploit it any time or even ever on his new models. But at least we know that Harley is preoccupied by the heating issues created by bigger air-cooled engines and tres to find a way to make them evolve without changing too much its Big Twin engine design.