8-
1-2
PI
LOT 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 fuel-air mixture is fed to the engine through the pilot outlet and the by-pass.
At idling speed, the fuel is mainly fed from the pilot outlet.
D
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 sup-
plied to the engine.
8-1
-4
CHOKE
The choke is used for easy start in the cold season. 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 pro-
per flow of
air
and fuel, the carburetor must be kept clean at all times. The carburetor disassembly and re-
assembly procedures are
as
follows: (See Fig.
39.)
b
8-2-1 THROTTLE SYSTEM
1)
Remove the Philips screw
(5)
and throttle valve
2)
The spring
(1
2)
can be taken out
by
removing
*Exercise care not to damage throttle valve ends.
(4),
and pull out the throttle shaft
(9).
the throttle stop screw
(1
3).
8-2-2 CHOKE SYSTEM
1)
Remove the Philips screw
(2)
and choke 'valve
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
(8)
and
(1
4)
at
the
right position.
(3),
and pull out the choke shaft
(7).
8-2-3 PILOT SYSTEM
1)
Remove the pilot jet
(6),
using correct tool to
2)
Reassembly
avoid damage to it.
Tighten the pilot jet securely. Otherwise, the fuel
may leak, causing engine malfunction.
Fig.
39
-
33
-
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