8-1
-2 PILOT SYSTEM
The pilot system feeds the
fuel
to
the engine during idling and low-speed operation.
The fuel
is
fed through
the
main jet
to
the pilot jet, where
it
is
metered,
and
mixed
with
the air metered
by the pilot air jet.
At the idling speed, the fuel
is
mainly fed from the pilot outlet.
0
The fuel-air mixture
is
fed to the engine through the pilot outlet and the by-pass.
8-1-3
MAIN
SYSTEM
The main system feeds the fuel to the engine at medium-and high-speed operation.
The fuel
is
metered by the main jet and fed to the
main
nozzle. The air metered by the main air jet
is
mixed with the fuel through the bleed holes
in
the main nozzle, and the mixture
is
atomized out of the
main bore, It is mixed again with the air taken through the
air
cleaner into an optimum fuel-air mixture,
which
is
supplied to the engine.
8-1-4 CHOKE
The choke may be used
for
easy start when engine
is
cold. When the engine is cranked with
a
closed
choke, the negative pressure applied to the main nozzle increases and
draws
more fuel accordingly
this
starting up the engine more easily.
8-2 DISASSEMBLY AND REASSEMBLY
Apart from mechanical failures, most of carburetor troubles are caused by
an
incorrect
mixing
ratio,
which may arise mainly due to a clogged up air
or
fuel passage
in
jets,
or
fuel level variations.
In
order to
assure
proper flow
of
air and fuel, the carburetor
must
be
kept clean at
all
times. The carburetor
disassembly and reassembly procedures are
as
follows
:
(See Fig.
8-3.)
8-2-1 THROTTLE
SYSTEM
(1)
Remove the philips screw
(1)
and throttle valve
(2)
The spring
(4)
can be taken out by removing the
*
Be
careful not to damage the throttle valve
rim.
(2),
and pull out the throttle shaft
(3).
throttle stop screw
(5).
8-2-2
CHOKE
SYSTEM
(1)
Remove the philips screw
(6)
and
choke valve
(7),
and pull out the choke
shaft
(8).
(2)
When reassembling the choke shaft, make
sure
that the cutout
in
the choke valve faces the
main
air jet.
Meanwhile, when reassembling
set
the rings
(9)
and
(10)
at the right position.
8-2-3 PILOT SYSTEM
14
16
15
17
19
A
(1)
Remove the pilot jet
(ll),
using proper
tools
to
(2)
Reassembly
avoid damage
to
it.
21
--@
Tighten the pilot jet securely. Otherwise, the fuel
13
.-e
may leak, causing engine malfunction.
18
12
Fig.
8-3
-
47
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