Scott started using water cooling in 1911, not '26. Mind you, they're pretty simple, AFAIK they are pure thermo-syphon with no pump, no thermostat and certainly no cooling fan!

The problem with aircooled engines is that the temperature varies due to variations in ambient temperature and use but more importantly, it varies across the engine. The cylinder head area runs the hottest but is also the most difficult to get the heat away from. In order to deal with these temperature variations some parts of the engine have to be carefully designed to avoid distortion caused by the differential expansion. In a watercooled engine the differential expansion is minimal, components can be made lighter and the engine can run a higher state of tune as heat dissapation is better. You should also get higher efficiency from watercooling as the tune (mixture/timing) can be set for a fixed engine temperature. Depending on the design watercooled engines are the one's more likely to overheat when stationary - especially enduro bikes which have the smallest possible radiator but even bikes with fans sometimes can't cope with high ambiant temperatures.

Aircooled engines should be designed such that they have sufficient fin area so they don't overheat when stationary for an extended period but this will obviosly depend on the ambiant air temperature as rate of heat transfer (which is fixed by fin area) is directly proportional to temperature difference. The crucial thing is if you leave you bike running in 40 degrees it will stabilise at a temperature 20 degrees higher than if the ambiant was 20 and does that 20 degrees extra cause the oil to start evapourating or breaking down - which in turn means oil changes and the correct grade (for the climate) are more important on aircooled bikes.

Simply, your fins are a heat sink.

Heat sink - Wikipedia, the free encyclopedia


They will still cool the engine while stationary but of course work better with air flow.

If you're engine is air cooled it will be because the engine will be able to take it with no issues. Low compression and low torque/HP engines don't produce enough heat for it to be a problem.

Although, didn't 'Lane Splitting' only become legal in some states of the U.S.A because those fat hogs were overheating in the summer while stuck in traffic ??

Urban legend ?

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According to the AMA, lane splitting in California is neither legal nor illegal---there is no law regarding it. Police just let it happen.