Adjusting Screws; Throttle Shaft With Lever - Stihl 4180 Series Service Manual

Hold end cover (32) with gasket (31) and pump
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diaphragm (30) up and fit it on the carburetor body –
making sure the gasket (31) and pump diaphragm
(30) do not move out of position.
Move the end cover (32) carefully back and forth until
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its pegs engage the holes in the carburetor body.
Insert and tighten down the screws (33).
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Install the carburetor, @ 10.2
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11.8

Adjusting Screws

There are three adjusting screws on the carburetor:
High speed screw H (14)
–
Low speed screw L (13)
–
Idle speed screw H (12)
–
If the carburetor cannot be adjusted properly, the problem
may be the adjusting screws.
Removing
Remove the carburetor, @ 10.2
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Unscrew the high speed screw (H) (14) and low
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speed screw (L) (13).
H L
14
13
Check tips (arrows) of high speed screw H (14) and
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low speed screw L (13) for damage or wear and
replace the screws if necessary.
Remove and inspect the idle speed screw (12),
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replace if necessary.
Installing
Fit the adjusting screws (12, 13, 14) and carry our
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basic setting, @ 11.2.
11.9

Throttle Shaft with Lever

Removing
Remove the screw (27) from the throttle shutter (45)
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and take out the shutter.
Remove the E-clip (28).
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Pull out the throttle shaft (43).
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Remove the sealing ring (42), washer (18) and spring
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(44) from the throttle shaft (43).
Series 4180 Powerhead
H
L
Installing
44
Push the spring (44) onto the throttle shaft (43) so that
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it locates in the notch on the lever.
Push the washer (18) and sealing ring (42) onto the
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throttle shaft (43) and up to the spring (44).
43
Use a scriber to push back the pump piston and push
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the throttle shaft (43) into the carburetor at the same
time.
Push the throttle shaft (43) into the carburetor until the
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long leg of the spring (44) engages the recess in the
carburetor (arrow).
Fit the E-clip (28).
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43
42
18
43
29