Harley-Davidson engines primarily use air cooling as the primary method of keeping the engine temperatures within acceptable limits. Air-cooled engines rely on the flow of air over the engine's fins to dissipate heat and maintain optimal operating temperatures.
Historically, most Harley-Davidson motorcycles have been equipped with V-twin engines, which feature large surface areas and fins on the cylinder heads and engine cases. These fins increase the surface area exposed to the air, allowing for better heat dissipation. The air-cooling method is often associated with the distinctive appearance of Harley-Davidson engines, characterized by the visible fins and classic aesthetic.
While air cooling is the primary method, some Harley-Davidson models, particularly those in their touring line-up, may incorporate additional components to assist with cooling. These additional components can include oil coolers, which help dissipate heat from the engine oil, and sometimes, Harley-Davidson's Twin-Cooled system, which incorporates both air cooling and liquid cooling for enhanced cooling performance.
It's worth noting that liquid-cooled engines are becoming more prevalent in certain Harley-Davidson models, especially in their newer line-up like the Street and Pan America models. These liquid-cooled engines use a combination of air and liquid cooling to regulate engine temperatures more effectively, particularly in situations where the engine is subjected to higher loads or operating in hotter environments.