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F
UE L SYSTEM
187
J
et
Needle
Adj ust men t
Adjust the
position
of
the jet needle
to
a
ffe ct the
air/fuel mixture
for medium
throttle
openings.
I. Remove thecarburetoras described
in
this chapter.
2.
Remove the
screws securing the cover (Figure
56).
3.
Remo
ve the
cover and
the
spring.
4.
Care
fully
withdraw
the throttle valve/diaphragm
assembl y (Figure
57).
5.
To
disassemble
the
throttl
e
valve/diaphragm
as-
sembly, per
form
the
following:
a.
Slowly
push
the jet
needle
up to
dislodge the
upper
nng.
b. Re
move
the
upper
ring, jet need le, E-ring
and
...- -
low
er
ring (Fi gure
58)
.
6. Remove
the E-ring
and
lower
ring
from the jet
needle.
7.
Refer
to
Ta
b le
I
for
standard
size
j
et
ne
ed
le
and sta nda rd E-ring
location
from
the
top
of
the
j
et
need le.
NO
TE
Record the
clip
pos
ition p
rio r
to re-
mo
va
l.
8. Raising the
needle
(low ering
the E-ring) will
enrichen
the
mi
xture during
mid-throttl
e opening,
while
lowering the needle (raising
the E-ring)
will
lean
the
mixture.
9.
Install
the
j
et
needl e,
vacuum
slide
and
dia-
phragm as described
in
this
chapter.
10. Perform Steps 14-
19
of
Carburetor
Assemblv
in
this
chapter.
Main Jet
Replacement
The
size
of tile
main
jet
affects the
air/fuelmixture
during
wide
-open
throttle
operation.
Different size
mainjetsare available
and
can
be installed
tochange
the
mixture
for
operation
at
high
engine
speeds.
The carburetor
assembly must
be
removed
and
partially
disassembled
to
remove the
main
jet.
I
.
Remove
the carburetoras described
in
this
chapter.
2.
Remove
the
mounting
screws and
remove the
float
bowl
(Figure 53) and
O-ring
gasket.
3.
Unscrew and remove
the
main jet (Figure
59
).
4. Do not remove the spacerring
underthe
mainjet.
5. The
size
is
stamped
on
the
jet. The
mainjet
size
listed in Table
1 is recommended
for
operation
at
ambi
ent temperat ures
of
5-26"
C
(40-80"
F) and at
a
ltitud
es
of
0-900
m (0-
3000
tt
.).
A smaller size
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