Honda CB160 Shop Manual page 53

3. 13 CARBURETOR
4.
Jet needle
The jet needle, with the needle jet, adjusts the
mixture ratio at mid-throttle. The jet needle with c
long taper section is float fitted at the center hole of
the throttle valve and the taper at the tip enters
the needle jet. According to the position of the
. throttle valve, the flow amount fuel is increased or
decreased through the taper and a suitable flow
amount {a suitable mixture) is obtained. The jet needle
has five grooves for positioning. Lowering the posi-
tion from the first step to the fifth, density of the
mixture becomes heavier. (Refer to fig. 3. 140)
5.
Throttle valve
The throttle valve adjusts the air fed to the engine
for setting speed and output. In addition, it also
adjusts the mixture. There is a cutaway at the air
intake side of the throttle valve and by changing the
size of the cutaway {number) the negative pressure
is changed the fuel flow and mixture ratio is changed.
However, the cutaway range covers mainly from idling
to around
1 /
4 throttle, with little influence above l /2
throttle.
(Refer to fig. 3. 141)
6. Slow speed jet
The slow speed jet controls the fuel flow at idling
and low throttle, and produces a mixture with the air
coming from the air breeding hole ; it vaporizes the
fuel.
(Refer to Fig. 3. 142)
7. Air screw
The air screw controls the air flow entering the
slow speed system. By adjusting air mixed in fuel
coming frotn the slow speed jet, it produces a proper
mixture and ejects the mixture from the tip of the
slow speed jet.
(Refer to Fig. 3. 143)
Fig. 3. 140 Jet needle
Fig. 3. 141 Throltle valve
Fig. 3. 142 Slow speed jet
fig.
3. 143 Air screw
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