8-1-2
PlLOT 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.
The fuel-air mixture
is
fed to the engine through the pilot outlet and the bypass.
At
idling speed, the fuel
is
mainly fed from the pilot outlet.
/”.
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 is used for easy start when engine
is
cold. When the starter is operated with a closed
choke, the negative pressure applied to the main nozzle increases and draws much fuel accordingly
;
thus easily start up the engine.
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.
71.)
8-2-1
THROTTLE SYSTEM
(1)
Remove the philips screw
(
10)
and throttle
valve (1
11,
and pull out the throttle shaft
(30).
(2)
The spring
(17)
can be taken out by removing
the throttle stop screw
(16).
*Exercise care not to damage throttle valve
ends.
8-2-2
CHOKE SYSTEM
(I)
Remove the
philips
screw
(14)
and choke valve
(131, and pull out the choke shaft
(31).
(2)
When reassembling the choke shaft, make
sure
that the cutout in the choke valve faces. the
main air jet.
Meantime, when reassembling set the rings
(32) and
(34)
at the right position.
8-2-3
PILOT SYSTEM
Remove the pilot jet
(181,
using correct tool
to avoid damage to
it.
Reassembly
Tighten the pilot jet securely. Otherwise, the
fuel
may
leak, causing engine malfunction.
28
29
Fig.
72
-
46
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