URAL Motorcycles Bavarian Classic 2001, Owner'S Manual

Page: 101 / 105

101
Theory of Operation
When the engine is running, pulsating negative pressure is created at the carburetor inlets and the
air box. This negative pressure is passed through a 1-way valve where it is converted into a con-
stant vacuum. The vacuum is passed through the energized electric valve to the butterfly valve
actuator. This vacuum causes the actuator to open the butterfly valve. This action allows outside air
to enter the air box.
The pulsating negative pressure from the carburetor inlets is also passed to another 1-way valve
where it is converted to a constant vacuum. This vacuum is then used to open the breather valve.
When the breather valve is open, it allows atmospheric pressure to enter the carburetor vent lines
to allow the carburetor float valves to operate normally.