In air-cooled engines, the cylinder block and the cylinder head are made with deep fins on the outside.
(1) The top of the heat sink on the air-cooled cylinder is wider and generates the most heat.
(2)The horizontal air-cooled engine has a cooling duct for the fins.
(3) Horizontal air-cooled engines have cooling ducts to the fins.
Air-cooling through fins
(1)The top of the heat sink on the air-cooled cylinder is wider and generates the most heat
(2) Horizontal air-cooled engines have cooling ducts to the fins.
(1) Fins on an air-cooled cylinder are wider at the top, where most heat is generated.
(2)Water-valve heating system
In the heater operated by the water valve, all air passes through the substrate. The substrate temperature is controlled by adjusting the amount of hot water passing through it.
Frequently a duct runs all around the fins, and an engine-driven fan blows air through the duct to take heat away from the fins.
A temperature-sensitive valve controls the amount of air being pushed around by the fan, and keeps the temperature constant even on cold days.
Cooling the oil
Air-cooled engines and high-performance water-cooled engines have an additional small radiator in addition to the water radiator, through which engine oil is cooled.