KTM 400-660 LC4 1998-2005, Repair Manual

Page: 201 / 501

Repair manual KTM LC4
Art.-Nr
. 3.206.014 -E
8-37E
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 data 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 will decrease
again. Adjust the point of the highest idling speed between these
two positions. If, in the course of this procedure, the speed
undergoes a relatively 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.
a) If the mixture control screw has been screwed in up to the stop
without causing any change in rotational speed, a smaller idling jet
has to be installed;
b) If 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 adjusting
work from the beginning.
5 Then, use the adjusting wheel to set the desired idle speed.
6 In cases of greater changes in outside temperature and extremely
different altitudes, the idling speed should be readjusted.
1
2
2