Honda CB160 Shop Manual page 52

48
Fig. 3. 136 Float chamber
Fig. 3. 137 Choke
Fig. 3. 138 Main jet
Fig.
3. 139 Needle jet
FLOAT
ARM PIN
FLOAT
3. ENGINE
3. Float chamber
As
previously stated, the carburetor produces mixed
gas suitable by opening and closing the throttle for
all speeds of the engine. Hence,
it
is necessary to
keep the fuel level constant ; the float chamber plays
this role. Fuel fed from the tank passes through the
passage between valve and enters the float chamber.
The float becomes buoyant as fuel enters and pushes
up the valve through the float arm ; when the valve
contacts the valve seat, the flow of fuel stops. When
the level decreases due to consumption of fuel, the
float drops corresponding to the change and the valve
opens for allowing fuel to enter the float chamber.
By repeating this operation, the fuel level is held
constant. (Refer fo Fig. 3. 136)
4. Choke
As shown in the figure, the choke valve closes at
the position where the choke lever is pushed up and
opens at the position where the choke lever is
lowered. (Refer to Fig.
3. 137)
B.
Operation of component parts
1. Main jet
The main purpose of this unit allows adjustment of
the mixture ratio by controlling the flow of fuel with
the throttle fully opened. However, the jet influences
the mixture ratio, not only at full throttle, but also at
other points. (Refer to Fig.
3. 138)
2.
Air jet
For insuring that the mixed gas does not become
excessively heavy at fully throttle and high speed,
and that it does not become excessively thin at redu-
ced throttle and low speed, bleeding air is fed into
the needle jet holder. The air jet controls this amount
of air. At a certain throttlle opening, a larger air
jet produces a smaller difference of fuel flow between
high and low speed ; the flow decreases.
3. Needle jet
This unit readjusts the adjusted fuel by the main
jet at full throttle and medium speed. Adjustment
is
simultaneously performed with that of the needle jet.
. The hole diameter is highly precise. (Refer to Fig.
3. 139)