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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 98 respectively 95 MOZ).
Mixing ratio 2-stroke motor oil : super fuel 1:40 (125/200), 1:40 – 1:60 (250/300/380).
Basic information on a change of 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 car-
buretor. Experience has shown that adjusting the main jet, the idling jet and the jet needle is sufficient and that changes of other parts of the carbu-
retor 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
,
ENGINE FAILURE
AND USE OF SAME 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
.
PLUG
– I
N THE CASE OF A LEANER ADJUSTMENT OF THE CARBURETOR PROCEED CAUTIOUSLY
OVERHEATING AND PISTON SEIZURE
NOTE:
If despite a changed adjustment the engine does not run properly, look for mechanical faults and check the ignition system.
Basic information on carburetor wear
As a result of engine vibrations, throttle valve, jet needle, and needle jet are subjected to increased wear. This wear may cause carburetor malfunc-
tion (e.g., overly rich mixture). Therefore, these parts should be replaced after 10000 kilometers (6000 miles).
2
WARNING
ROZ 98
95
RESPECTIVELY
MIXED WITH HIGH
.
(i. e. Shell Advance Racing X).
.
Definitions
Mixture too rich:
Too much fuel in proportion to air.
Mixture too lean:
Not enough fuel in proportion to air.
1
Idling range
Operation with closed throttle valve. This range is influenced by the position of the
air control screw
the engine is hot.
To this end, slightly increase the idling speed of the engine by means of the idle
adjusting screw. Turning it clockwise produces a higher idling speed and turning
the screw counterclockwise produces a lower idling speed. Create a round and sta-
ble engine speed using the air control screw (basic position of the air control screw
main jet
= open by 1.5 turns). Then adjust to the normal idling speed by means of the idle
jet needle
adjusting screw.
Opening up
jet needle
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 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
idle jet
carburetor will be too rich, the fuel level too high or the float needle is leaking.
throttle valve
air control screw
idle adjusting screw
choose leaner carburetor adjustment
choose richer carburetor adjustment
-
-
GRADE TWO
STROKE ENGINE OIL
. U
,
SING TOO MUCH OIL
THE ENGINE CAN START SMOKING AND FOUL THE SPARK
. A
LWAYS REDUCE THE JET SIZE IN STEPS OF ONE NUMBER TO AVOID
A
1
and the idle adjusting screw
B
. O
THER TYPES OF GASOLINE CAN CAUSE
2
. Only make adjustments when
23
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