Carburetor Heater

[Volfy]

It also has to do with the fuel atomizing inside the carb. The absorption of latent heat of evaporation causes temps to drop below the prevailing dew point, and condensation occurs.

[dakota_c69]

Here's the best explanation I've heard so far -

Carb ice, and why our bikes run lousy is solely dependent on the relative humidity of the air on any given day. As the air gets sucked through the Venturi of the carb the pressure drops and so does the temp of the air. When the air temp reaches the magic dew point moisture from the air precipitates out and since it's so cold freezes on any surface it may strike as it rushes through the carb. I think I'n the average motorcycle carb it either coats the top if the pilot jet first or disrupts the airflow over it. This can be combated I'n several ways, either heat the air before it goes through the carb so it doesn't drop temp enough to get to the dew point, or heat the inside surfaces so that the supercooled water droplets (they will freeze when they hit something) thaw immediately and run through the engine.

Unfortunately when your carb starts to act up due to internal freezing and airflow disruption, the bike tends to run rich which makes your bike run cooler which reduces the chance that residual heat from the cylinder can migrate back through the carb when you've stopped for a break.

From the keyboard of ThirtySeven - This guy ---> https://www.youtube.com/watch?v=ryu6Pt4-rAs