I couldn't find this answer nowhere, but i'm very curious about why some motorcycles have a carburetor intake connected to their chassis.
In the image below we can see how the chassis is designed with holes in the lateral/front part of the chassis, to channel the intake air that come through the air filters.
Just for context, this is the whole motorcycle:
Any idea why a design like this exists at all?
It puts the filter up high and the use of the already existing frame tubes reduces the need for extra pipes that would be a large diameter.
Frame tubes have also been used for storage of oil.
It’s done because air cooled engines heat the air and fuel (reducing density)in the “breathing zone” of the carbs during no, and low speed operation. Higher velocity air is more dense when compared to slower moving air. Really just a way to designate and deliver a consistent air charge. Potentially less effected by the heat radiating off the cooling fins. At least in the short term. I’ve even seen designs that include directed intake air flow over fuel petcocks enroute to the throttle bodies. If you look at the carb placement between the two hottest components on the engine. Fuel is just as susceptible to density loss as temps rise. If you note the majority of the gas tank sits above this air cooled section of the frame rails. Also in an attempt to reduce heat rising and conduction through components.
