Carburetor - Adjusting Idle - KTM 2014 Freeride 250 R Owner's Manual

17 TUNING THE ENGINE
17.4

Carburetor - adjusting idle

Idle air range A
Operation with the throttle slide closed. This range is influenced by adjusting screw
and the idle air adjusting screw
Transition range B
Behavior of the engine when the throttle slide is being opened. This range is influenced
by the idling jet and by the form of the throttle slide.
If the engine sputters and smokes heavily when it starts despite a good idle and part-
load setting, and if it abruptly reaches full power at a high rpm, the carburetor setting
is too rich, or the float level is too high or the float needle valve is leaky.
Part-load range C
500282-01
Operation with the throttle slide partially open. This range is influenced by the jet
needle (form and position). The idle setting influences the engine tuning in the lower
range, and the main jet influences the engine tuning in the upper range.
If the engine stutters when accelerating with a partially open throttle slide, the jet nee-
dle must be lowered by one notch. If the engine knocks when accelerating at the full
power rpm range, the jet needle must be raised. If the above events occur on idle or
just above it, the idle system must be set to a leaner setting if the engine is stuttering
or to a richer setting if the engine is knocking.
Full-load range D
Operation with the throttle slide open (full throttle). This range is influenced by the
main jet and jet needle.
If the insulator of a new spark plug is very light or white after a brief ride at full throt-
tle, or if the engine knocks, a larger main jet needs to be used. If the insulator is dark
brown or sooty, a smaller main jet needs to be used.
x
–
Screw idle air adjusting screw
ting.
Guideline
Idle air adjusting screw
Open
–
Run the engine until warm.
Guideline
Warm-up time
B01675-10
Danger
Danger of poisoning Exhaust gases are toxic and inhaling them may result
in unconsciousness and/or death.
–
–
Adjust the idle speed with adjusting screw
Guideline
Choke function deactivated – The choke lever is pushed in to the stop. (
Idle speed
–
Turn idle air adjusting screw
–
Note the position and turn the idle air adjusting screw slowly counterclockwise until
the idle speed falls.
–
Adjust to the point between these two positions with the highest idle speed.
Info
If there is a big engine speed rise, reduce the idle speed to a normal level
and repeat the above steps.
If the procedure described here does not lead to satisfactory results, the
cause may be a wrongly dimensioned idling jet.
If you can turn the idle air adjusting screw to the end without any change of
engine speed, you have to mount a smaller idling jet.
After changing the idling jet, start from the beginning with the adjusting
steps.
Following extreme air temperature or altitude changes, adjust the idle speed
again.
.
2
all the way in and turn to the specified basic set-
2
When running the engine, always make sure there is sufficient ventila-
tion, and do not start or run the engine in an enclosed space without an
effective exhaust extraction system.
slowly clockwise until the idle speed starts to drop.
2
2.0 rotations
≥ 5 min
.
1
1,400... 1,500 rpm
83
1
p. 15)