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.
The fuel-air mixture is fed .to the engine through the pilot outlet and the by-pass.
During engine idling, the fuel is mainly fed from the pilot outlet.
8-
1-3
MAIN SYSTEM
The main system feeds the fuel to the engine during 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 in the cold season. When the recoil starter
is
pulled 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.
41
.)
18
8-2-
1
THROTTLE
SYSTEM
1)
Remove the Philips screw (1
8)
and throttle valve
2)
The spirng
(21)
can be taken out by removing
*Exercise care not to damage throttle valve ends.
(19), and pull out the throttle shaft
(20).
the throttle stop screw (22).
8-2-2
CHOKE
SYSTEM
1)
Remove the Philips screw
(14)
and
choke valve
(1
S),
and pull out the choke shaft
(1
6).
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
Remove the pilot jet (23) using correct tool to
avoid damage to it.
Reassembly
Tighten the pilot jet securely. Otherwise, the fuel
may leak, causing engine malfunction.
17
7
12
A
Fig.
4
1
-
27
-
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