Carburetor Adjustment; Adjusting Idle Speed; Part/Full Throttle Range - KTM 65 SX 2003 Owner's Manual

Carburetor adjustment *

Basic information on the original carburetor setting
The original carburetor setting was adapted for an altitude of approx. 500 meters (1600 ft.) above sea level, and the ambient
temperature of approx. 20° C (68° F), mainly for off-road use and central European premium-grade fuel (ROZ 95).
Mixing ratio 2-stroke motor oil : super fuel 1:40 .
Basic information of changing the carburetor setting
Always start out from the original carburetor setting. Essential requirements are a clean air filter system, air-tight exhaust system and
an intact carburetor. Experience has shown that adjusting the main jet, the idling jet and the jet needle is sufficient and that changes
to other parts of the carburetor will not greatly affect engine performance.
RULE OF THUMB: high altitude or high temperatures
low altitude or low temperatures
– O -
NLY USE PREMIUM GRADE GASOLINE
,
FAILURE AND THEIR USE WILL VOID YOUR WARRANTY
– O - 2-
NLY USE HIGH GRADE STROKE ENGINE OIL OF KNOWN BRANDS
– N -
OT ENOUGH OIL OR LOW GRADE OIL CAN CAUSE EROSION OF THE PISTON
.
THE SPARK PLUG
– I
N THE CASE OF A LEANER ADJUSTMENT OF THE CARBURETOR PROCEED CAUTIOUSLY
OVERHEATING AND PISTON SEIZURE
NOTE: If the engine does not run properly, despite a changed adjustment look for mechanical faults and check the ignition system.
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
carburetor malfunction (e.g. overly rich mixture). Therefore, these parts should be replaced after 1000 hours of using.
WARNING
ROZ 95 -
MIXED WITH HIGH
.
(
I
.
Idling range – A, Adjusting the idle speed
Operation with closed throttle valve. This range is influenced by the idle
adjusting screw
The idling speed can be changed by turning the idle adjusting screw.
Turning it clockwise produces a higher idling speed and turning the screw
counterclockwise produces a lower idling speed.
Opening up – B
Engine behavior when the throttle opens. The idle jet and the shape of the
throttle valve influences this range. If, despite good idling-speed and
1
part-throttle setting, the engine sputters and smokes when the throttle is
fully opened and develops its full power not smoothly but suddenly at high
engine speeds, the mixture to the carburetor will be too rich, the fuel level
too high or the float needle is leaking.
Part-throttle range – C
Operation with partly open throttle valve. This range is only influenced by
main jet
the jet needle (shape and position). The optimum part-throttle setting is
jet needle
controlled by the idling setting in the lower range and by the main jet in the
upper range. If the engine runs on a four-stroke cycle or with reduced power
when it is accelerated with the throttle partly open, the jet needle must be
jet needle
lowered by one notch. If the engine pings, especially when accelerating
under full power at maximum engine revs, the jet needle should be raised.
If these faults should occur at the lower end of the part throttle range at a
four-stroke running, make the idling range leaner; if the engine pings, adjust
idling jet
the idling range richer.
throttle valve
idling jet
Full throttle range – D
Operation with the throttle fully open (flat out). This range is influenced by
the main jet and the jet needle. If the porcelain of the new spark plug is
found to have a very bright or white coating or if the engine rings, after a
short distance of riding flat out, a larger main jet is required. If the porcelain
is dark brown or black with soot the main jet must be replaced by a smaller
one.
choose leaner carburetor adjustment
choose richer carburetor adjustment
- . O
GRADE TWO STROKE ENGINE OIL
. . S A R X).
E HELL DVANCE ACING
. I
F YOU USE TOO MUCH OIL
. A
LWAYS REDUCE THE JET SIZE IN STEPS OF ONE NUMBER TO AVOID
1
. Only make adjustments when the engine is hot.
THER TYPES OF GASOLINE CAN CAUSE ENGINE
,
THE ENGINE CAN START SMOKING AND FOUL
29