URAL Motorcycles Bavarian Classic 2001, Owner'S Manual

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Electric Valve
The electric valve has two states. In it’s resting state, the valve vents the butterfly valve to atmo-
spheric pressure. This will cause the butterfly valve to close and seal the intake manifold to outside
air. In it’s active state, the electric valve passes negative pressure from the 1-way valve to the
butterfly valve actuator causing the butterfly valve to open. This will then allow outside air to enter
the engine intake manifold.
1-Way Valve
The 1-way valve allows gas flow in one direction only. This converts the pulsating negative pressure
from the carburetors into a constant negative pressure for operating the various pneumatic de-
vices.
Breather Valve
The breather valve is operated by negative gas pressure. The breather valve has two states. In it’s
resting state, the valve seals the carburetor vent lines from outside air. During engine operation,
negative pressure from the accompanying 1-way valve activates the breather valve and opens the
carburetor vent lines to atmospheric pressure. This allows the carburetor float valves to operate
normally.
Air Box
The air box is a sealed container, which conducts outside air to the engine intake manifold through
the air filter. This is required to ensure that air-borne contaminants may not enter the engine and
damage any internal components.
Restrictor
The restrictor passes only very low flow rates of gas. This performs two functions. It prevents
negative pressure present at the air box during acceleration from being transmitted to the carbure-
tor vents, causing the carburetors to overfill with gasoline. It also conducts atmospheric pressure to
the carburetor vents when the engine is at rest, to enable the carburetor float valves to stop the
supply of gasoline to the carburetors.