Fuel System
4) Choking Passage (#2 and #3 carburetor)
e
b d
f
a
g
å
k
∫
c
h
j
i
a - Air intake h - Fuel inlet
b - Air-bleed inlet i - Main jet
c - Slow air jet j - Slow jet
d - Bypass port k - Choke valve
e - Pilot screw å Air
f - Idle Port ∫ Air-fuel mixture
g - Throttle valve
Choke system consists of choke valve, detent and push-pull. When starting cold engine, the operator should judge whether it is
necessary to operate the choke to make engine starting easier, and if necessary, to operate the handle of choke cable manually
to set it to a proper position.
When attempting to start cold engine, pull choke lever to close choke valve. When engine starts, low pressure (vacuous)
area is formed in the venturi on the back of choke valve. Then, the fuel goes through main nozzle, bypass port and idle port,
and sucked into carburetor bore, where it is mixed with air that runs in from opening of the choke valve to form thick air-fuel
mixture.
As engine warms up, operate choke cable manually to open choke valve. When engine has warmed up to a temperature
suitable to the operation. Set choke lever to its original position.
4-16
2st 50D2 2011
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