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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
sup
plied 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 failusres, 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.
5
1
.)
8-2-
1
THROTTLE SYSTEM
1)
Remove the Philips screw
(33)
and throttle valve
(28), and pull out the throttle shaft
(29).
2)
The spring
(30)
can be taken out by removing
*Exercise care not
to
damage throttle valve ends.
the throttle stop screw
(3
1).
8-2-2 CHOKE SYSTEM
1)
Remove the Philips screw (22) and choke valve
(23), and pull out the choke shaft
(24).
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
(26)
and
(27)
at the right position.
8-2-3
PILOT
SYSTEM
1)
Remove the pilot jet
(32),
using correct tool
to
2)
Reassembly
avoid damage to it.
Tighten the pilot jet securely. Otherwise, the fuel
may leak, causing engine malfunction.
Fig.
51
17
-
34
-