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0725-156
. Pilot
Oullet
A larger numbered pilot jet will allow more fuel
(richer) while a smaller number will provide less
fuel (leaner).
0725-158
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Fig. 5-10
Fig. 5-9
72
Adjustment of the air screw is done with the
engine idling. The screw is adjusted until the
engine runs smoothly. Generally, the adjustment
should range from 1 to 2-1/2 turns from a seated
position. If it takes less than one turn, the pilot jet
is too small and should be replaced with a larger
pilot jet. If it takes 2-1/2 turns or more, the pilot jet
is too large and should be replaced with a smaller
pilot jet.
Pilot Jet and Air Screw
The pilot jet circuit controls the incoming fuel
mixture when the throttle valve is from 0 to 1/8
open. The amount of gasoline contained in the
low speed mixture is metered by the pilot jet. The
air is controlled by the air screw.
Examine the throttle valve for imperfections
in casting or "score" marks on slide surfaces.
The fuel level in the float chamber is controlled by
tt-
rejection of the two float arms. If there is dirt
b,
den the needle valve and seat, causing the
valve to stay open, fuel will overflow. Also, wear or
damage in the needle valve area, or a damaged
float, will cause the fuel to overflow.
1.
Examine the carburetor body, float bowl and
mixing chamber cap for cracks, nicks,
stripped threads and any other imperfections
in the casting.
Internal
Adiustments
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An air leak lJetw;en the carburetor and engine
will
cause severe
engine damage.
3.
Check condition of the-throttle return spring.
4.
Inspect floats for holes or damage.
5.
Inspect all gaskets and O-rings for distortion,
tears or noticeable damage.
6. - Inspect jet needle and air screw for damaged
tips.
9.
Check carburetor insulator block for distor-
tion by placing it on a surface plate. If only
slightly distorted, sand it flat. If excessively
distorted, replace the block.
8.
Inspect starter plunger and seat for wear or
damage.
7.
Inspect tip of inlet needle valve.
10. Check carburetor mounting flange. If the
flange is warped, replace the flange.
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