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Slow adjuster adjustment
Fig. 2-33
1) Procedure for adjustment
a) Set the slow adjusting screw and the main adjusting
screw to specification at the same time
.
Settings at factory
:
Settinas at factorv
GPX338F
Slow adjust ing screw
(L, R)
3/4
Main adjust ing screw
(L,
R) 1.0 +
1/
8
Pilot jet
#85
b) Turn the slow adjusting screw in or out
1/
8 turn
each time, until the engine idles fast.
c) Back out the slow adjust ing screw additional
1/
8
±
1/4 turn to provide enough fuel for proper accelera-
tion.
d) Perform a runn ing test, and warm up the engine
again.
Then adjust the idle adjusting screw so that the en-
gine runs at the specified idling speed.
(3) Pilot jet adjustment
If the standard p
i
lot
j
et (#85) can not maintain
smooth engine performance at low altitudes below
33.8° F, the spare pilot jet (#95) should be used.
(Fig. 2-34)
1.
Pil ot
jet
Fig. 2-34
-
19
-
ENGINE -
Carburetor
(4) Main adjusting screw adjustment
The main adjusting screw controls the mixture when
the snowmobile runs at speeds from medium to
high.
It should be adjusted so that the engine runs
smoothly with the richest possible mixture.
This is very important in order to prevent the engine
from overheating
.
1) Procedure for adjustment
a) Back o.ut the main adjusting screw as specified.
Turns out
:
1
±
1/8
b) Perform a running test.
To test, accelerate the
snowmobile by quickly pulling the throttle lever to
full-throttle position from idling position
.
c) Perform a high-speed runn ing test, and find the posi
-
tion of the main adjusting screw where the engine
performance is the best.
The adjustment should be
made by turning the adjusting screw 1/8 turn each
time.
d) After the high-speed running test, check the spark
plug for discoloration.
Adjust the main adjusting
screw so the spark plug porcelain has a tan color at
maximum high speed load.
e) Keep the snowmobile running at high speed, and
test the engine operating condition
.
Repeat the
operations a) to c) above, and set the main adjusting
screw in the best position to achieve good spark
plug color.
Note:
If the main adjusting screw setting by the factory is
improper (causing the mixture too rich or too lean).
an adjustment should be started
with
the position
where it is back out about 1/4 turn from factory
specification.
(Fig
.
2-35)
Fig. 2-35
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