WM 80 Repair
Carburetor Basics
wc_tx000522gb.fm
61
5.5
Bing Carburetor Operation
See Graphic: wc_gr002897
Fuel Feed:
The Bing carburetor does not use a fuel pump; instead, the fuel supply
is gravity fed. A priming button
(a)
is used during the initial start-up to
manually open the inlet needle valve
(b)
which primes the fuel chamber
(c)
.
Inlet Needle Valve:
While the engine is running, fuel flow into the fuel chamber is controlled
by the inlet needle valve. The inlet needle valve is operated by the
control diaphragm
(d)
. The control diaphragm is activated by the
vacuum created when air moves through the carburetor throat. A vent
to atmosphere provides the air pressure differential needed to create
the vacuum. This vacuum draws the control diaphragm towards the
carburetor throat and in turn opens the inlet needle valve allowing fuel
into the fuel chamber. Suction at the engine intake draws fuel out of the
fuel chamber, through the discharge ports into the carburetor throat.
As the fuel in the chamber is used up, atmospheric pressure pushes in
on the opposite side of the diaphragm pushing it towards the throat of
the carburetor. This diaphragm action lowers the inlet needle valve and
allows fuel to fill the fuel chamber. This fuel pushes the diaphragm
away from the carburetor throat and in turn closes the inlet needle
valve. In actual practice, the inlet needle valve assumes an averaging
position whereby the amount of the fuel entering exactly replaces the
amount being used.
b
c
d
e
a
f
g
h
wc_gr002897
Summary of Contents for WM 80
Page 1: ...0162695en 003 0610 0 1 6 2 6 9 5 E N Repair Manual Engine WM 80...
Page 4: ...Foreword 4 wc_tx001528gb fm...
Page 27: ...WM 80 Maintenance wc_tx000520gb fm 27 wc_gr001168 a b c d k i h...
Page 35: ...WM 80 repair Starting and Ignition wc_tx000521gb fm 35 wc_gr002882 a d e b c...
Page 41: ...WM 80 repair Starting and Ignition wc_tx000521gb fm 41 wc_gr002885 S N d a c b...
Page 43: ...WM 80 repair Starting and Ignition wc_tx000521gb fm 43 wc_gr002886 a d f f e k c g i h j b...
Page 63: ...WM 80 Repair Carburetor Basics wc_tx000522gb fm 63 Notes...
Page 65: ...WM 80 Repair Carburetor Basics wc_tx000522gb fm 65 d d d d d 1 2 3 e 4 f g 5 6 h wc_gr007414...
Page 71: ...WM 80 Repair Carburetor Replacement wc_tx000522gb fm 71 Notes...
Page 109: ...WM 80 Repair Disassembly and Assembly wc_tx000523gb fm 109 wc_gr002935 d a b e c d...
Page 111: ...WM 80 Repair Disassembly and Assembly wc_tx000523gb fm 111 wc_gr002937 a b d e c f...
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Page 123: ...WM 80 Repair Disassembly and Assembly wc_tx000523gb fm 123 h wc_gr002908...
Page 127: ...WM 80 Repair Disassembly and Assembly wc_tx000523gb fm 127 a wc_gr002910 b OK OK...
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Page 131: ...WM 80 Repair Disassembly and Assembly wc_tx000523gb fm 131 wc_gr002912 f e a h g d a b c a f e...
Page 133: ...WM 80 Repair Disassembly and Assembly wc_tx000523gb fm 133 a c d wc_gr002913 e b...
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