With the air-stream cooling, the engine is cooled purely by the air-flow swirling through its cooling fins, regardless of speed. Also in this case, all the parts of the engine should be cooled as evenly as possible.
Almost exclusive to two-wheeled vehicles is the possibility to arrange the cylinder/s in such a way that they stand directly in the passing air-stream. In the past there were even (transverse mounted) six-cylinder, air-
cooled, in-line engines.
A simple construction, low engine weight.
The cooling cannot be regulated by a thermostat. In straight-mounted, in-line multi-cylinder engines the rear cylinders have a disadvantage. The greater noise development,
compared with liquid cooling, can be somewhat reduced by placing vibration-damping rubber plugs between the cooling fins. 06/09