Adjustment Of L-Needle; Adjustment Of H-Needle - Husqvarna 181 Workshop Manual

4
Fuel system
A L
Adjust the idling speed by means of the throttle adjusting screw T. Try to
reach a position where the chain is just beginning to rotate, that is at a
comparatively high idling speed.
Put your r;ght ham-f on the front hand/e and make a fine adjustment of the L-
needle with your left hand.
Fine adjustment is made as follows:
1.
2.
3.
4.
5.
Screw in the L-needle slowly and the speed will increase. Screw in the
needle a little further and the speed will slow down again as the fuel supply
becomes too "lean". Notice the position of the needle at the highest speed.
Open the L-needle again and notice the highest position. Note that the
speed slows down at "richer" supply.
Adjust the L-needle to the highest speed position. Then open it equivalent
to 10 min on a clock-face to obtain a somewhat "richer" supply to aid
acceleration.
By means of the T-needle, adjust the idling speed to 2.300 –2.500 r/rein,
ensuring that the chain does not rotate when engine is idling.
Give full throttle a couple of times to check that the engine "responds". If
not, open the L-needle by abt
3
min. Check again.
A H
Adjust the high speed needle (H) as follows:
Apply full throttle by keeping a constant grasp of the throttle trigger. At
correct adjustment of the H-needle the engine should be fourstroking.
Screw in the H-needle slowly until there is no more fourstroking (position A).
Then screw the needle out equivalent to 10 min on a clock-face.
Check by means of eg revolution counter No. 5025146-02 that the high idle
speed does not exceed 12.500 r/rein.
Now the carburetor adjustment is completed and you may release your hold
of the throttle trigger.
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