Carburetor - Adjust Idling; Basic Information On Carburetor Wear; Adjusting The Mixture Control Screw - HUSABERG "05 Owner's Manual

MAINTENANCE WORK ON CHASSIS AND ENGINE
CARBURETOR – ADJUST IDLING *
Idling adjustment of the carburetor strongly affects the engine's starting
behavior. That is, an engine whose idling speed is adjusted correctly will
be easier to start than one whose idling speed has not been adjusted
correctly.
The idle speed is controlled by means of the adjusting wheel (1) and the
mixture control screw (2). The adjusting wheel is used to adjust the basic
setting of the slide. The mixture control screw is used to control the idle
mixture which arrives at the engine by way of the idle system. Clockwise
turning reduces the fuel quantity (lean mixture), counterclockwise turning
increases the fuel quantity (rich mixture).
To adjust idling correctly, proceed as follows:
1 Turn in mixture control screw (2) up to the stop, and turn it back out
to the basic position (see technical date-engine)
2 Warm up the engine
3 Use the adjusting wheel (1) to set the normal idle speed (1400 - 1500
rpm).
4 Turn mixture control screw (2) slowly clockwise until idling speed
starts to decrease. Memorize this position, and turn mixture control
screw slowly counterclockwise until the idling speed decreases again.
Adjust the point of the highest idling speed between these two posi-
tions. If, in the course of this procedure, the speed undergoes a rela-
tively high increase, reduce the idle speed to a normal level and repeat
the procedure specified in 4. Serious competitive racers will choose
a setting approx. 1/4 turn (clockwise) leaner than this ideal value
because their engine will heat up more when used in competitions.
NOTE: If you fail to obtain a satisfying result by following the
procedure described above, an incorrectly dimensioned idling
nozzle may be the cause. If:
a) the mixture control screw has been screwed in up to the
stop without causing any change in rotational speed, a smal-
ler idling jet has to be installed;
b) the engine dies when the mixture control screw is still open
by 2 turns, a larger idling jet needs to be selected.
Naturally, in cases of jet changes, you have to start your adju-
sting work from the beginning.
5 Then, use the adjusting wheel to set the desired idle speed.
6 In cases of greater changes in the outside temperature and extremely
different altitudes, the idling speed should be readjusted.

BASIC INFORMATION ON CARBURETOR WEAR

As a result of engine vibrations, the throttle valve, jet needle, and needle
jet are subjected to increased wear. This wear may cause the carburetor
to malfunction (e.g., overly rich mixture). Therefore, these parts should
be replaced after 200 hours.

ADJUSTING THE MIXTURE CONTROL SCREW *

The mixture control screw is used to adjust the idle mixture.
Turning the mixture control screw in a clockwise direction will reduce the
idle mixture, turning it in a counterclockwise direction will increase the idle
mixture.
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