Idle System Purge
The purge air through the purge valve pressurizes all the internal passages of the carburetor. The idle system passages get cleaned with the air passing through the main jet and the emulsion tube on its way to the idle mixture chamber under the plastic plug. On its way, the air scrubs off the remaining fuel and ethanol from all the passages all the way to the idle small opening inside the carburetor body. The transition system small openings get cleaned at the same time.