Honda Z50A Manual page 28

26
(2)
Next turn the air screw slowly back and forth to obtain the point of
highest rpm.
(3)
If the engine rpm has increased as resu It of section (2) above. reset
engine speed back to the proper rpm with the throttle stop screw.
(4) Once again manuplate the air screw to see if the rpm will be increased.
(5) If the speed should increase again, perform section (3) (4) above again.
the
the
However, the adjustment of the air screv; should be within 1
% ±Ys
of a turn.
b. Adjusting the slow speed
The fuel mixture adjustment between idle to
Ys
throttle opening is made by the
air screw and the cut away on the throttle valve.
(1) Air screw
Turning in the clockwise direction will produce a rich mixture.
(2) Throttle valve cut away
In the vicinity
Ys
throttle opening, there may be cases where the fuel mixture
cannot be adjusted by the air screw only. In such case, if the fuel mixture
is too rich. the throttle valve must be replaced with one having a cutaway of
a large number size and then readjust the air screw.
c. Adjusting intermediate speed
At the throttle opening range between
Ys-.%'
the fuel mixture adjustment is made
primary by the position of the jet needle steps and replacement of the cut away
of the throttle valve. However, changing the cutaway of the throttle valve will also
affect the throttle opening between the
~
to ~. therefore, the adjustment of the
intermediate speed by replacing the throttle valve cut away only is very difficult.
It is recommended that the adjustment for the intermediate speed be made by the
jet needle, and stay within the range of acceptable acceleration performance since
this would provide greater fuel economy.
d. Adjusting the high speed
While driving at high speed, if the speed increases when the choke is closed slightly,
it is an indication that the carburetor is set too lean. Progressively replace the
main jet with one of a large size and readjust the carburetor.
Note:
Main jet sizes are numbered in the following manner:
Above
~
100: 105. 110, 115
Below
~
100: 98, 95, 92, 90
If the speed drops when the choke is closed slightly, it indicates that the main
jet is either of the proper size or that it is too large, in which case. perform the
following check to make the determination.
o
Proper jet size
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Progressively replace the main jet with one of a smaller size until there is a drop •
in speed and the speed increases when the choke is closed slightly, the installed
jet is too small and should he replaced with one of a size larger. this is the proper.
jet size. •
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