Wacker Neuson WM 90 Repair Manual page 76

Sub Systems
Ref Description
13 Metering chamber
14 First idle hole
15 Second and third idle
holes
16 Idle needle
17 High-speed needle
18 Main nozzle
19 Venturi
20 Choke valve
wc_tx000390gb.fm
Comment
The metering chamber is the fuel storage compartment
that has the function of supplying fuel to the nozzle
holes and other parts.
The first idle hole is the only fuel supply hole that is
available when the engine is idling.
The second and third idle holes have the function of
supplying fuel when the throttle is at an intermediate
opening state between the idling state and the fully open
state.
The idle needle has the function of controlling the fuel
when the engine is at idling speeds and when the throt-
tle is at low speed position.
The high speed needle has the function of controlling
the fuel when the engine is operating at high speed and
when the throttle is at a high speed position.
The main nozzle is the hole through which fuel is
ejected when the engine is operating at high speed and
when the throttle is at a high speed position.
The venturi has the function of increasing the air flow ar
the nozzle section, thereby improving the atomization of
the fuel.
The choke valve has the function of shutting the suction
of air when the engine is started at a cold state, thereby
securing the temporary supply of rich fuel/air mixture.
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WM 90 Repair