Triumph Factory Experience.

[Easy-X]

I guess a test could be place a metal cylinder in the middle of a room (static air, no direct sunlight) and point a fan at it. After an hour test the temperature on the fan side and reverse side to see if there's a temperature differential.
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Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[MCN]

The greatest percentage of heat produced by an IC engine is ejected via the exhaust.
A much smaller percentage dissipates via the lube system and the cooling system.

The pressure differential created by air moving over a surface relates to the Bernoulli principle.

Venturi and wings use this principle.

When air passes around a surface it resists separation caused by any object placed in the 'airflow'.

If shaped like a wing, the air on one side has to accelerate over that surface to maintain its connection with air on the other side of the wing.
To accelerate, the air pressure reduces.
The reduced air pressure means the air with higher pressure pushes the wing in the direction of lowest pressure.

Suction is not a great word to describe physical phenomenon.

Push is a far more accurate description.

It is a common misconception due to how we 'observe' things.

Aerofoil/hydrofoil rely on high pressure to do the work.

(It's a similar argument when describing what pumps do. Realistically, pumps do not create pressure, pumps only create flow.

Resistance to flow is what creates pressure.
When talking in practical terms.

Air-cooled engines are waaaay more noisy than liquid cooled engines.
That is a major consideration for engines in equipment.
And Air-cooled engines and cetera, are cheaper to manufacturer. Less complex overall.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[MCN]