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
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.
by
the pilot air jet.
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 according1y;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.
8-2.)
8-2-1 THROTTLE SYSTEM
(1)
Remove the philips screw
(15)
and throttle valve
(2)
The spring
(19)
can be taken out
by
removing the
(14),
and pull out the throttle shaft(l3).
throttle stop screw
(20).
*
Exercise care not
to
damage throttle valve ends.
8-2-2
CHOKE SYSTEM
(1)
Remove the clip
(23)
and choke valve
(17),
and
pull out the choke shaft
(16).
(2)
When reassembling the choke shaft, make sure
that the cutout in the choke valve faces the main
air jet.
8-2-3 PILOT SYSTEM
(1)
Remove the pilot jet
(18),
using correct tool to
(2)
Reassembly
avoid damage to it.
Tighten the pilot jet securely. Otherwise, the fuel
may leak, causing engine malfunction.
13
24
-
10
@-"--11
Fig.
8-3
-
45
-
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