52 Series 4144 Components FC, FS, KM
– Fit the spring (1) on the choke 
shaft.
– Position the rotary knob (2) so 
that the flat in the knob's bore 
lines up with the flat side (arrow) 
of the choke shaft.
: Push the rotary knob (2) on to the 
choke shaft until it engages, and 
hold it in that position.
: Insert screw (arrow) and tighten it 
down firmly.
Check operation:
– Press down the rotary knob = it 
can be rotated counterclockwise.
– Turn the rotary knob back to the 
stop = it springs back to its 
original position 
– knob is locked.
– Reassemble all other parts in the 
reverse sequence.
545RA092 TG
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1
545RA011 TG
8.4.5 Adjusting Screws
There are three adjusting screws on 
the carburetor:
H = high speed screw (1)
L = low speed screw (2)
LA = idle speed screw (3)
If the carburetor cannot be adjusted 
properly, the problem may be the 
adjusting screws.
The high speed screw H and low 
speed screw L each have a limiter 
cap, which has to be removed 
before the screw is removed.
Always install new limiter caps.
– Remove the filter cover, b 5.1
It is not necessary to remove the 
carburetor to remove and install the 
adjusting screws. For the sake of 
clarity, however, the illustrations 
show the carburetor removed from 
the machine.
– See also carburetor 
troubleshooting, b 4.4
545RA012 TG
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1
2
Low speed screw
: Use special tool 5910 890 4501 
to pry the limiter cap (1) off the 
low speed screw.
Do not re-install used cap – always 
fit a new cap.
: Take out the low speed screw (1).
545RA013 TG
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545RA014 TG
1