3. Adjustments
USE AND MAINTENANCE MANUAL CHAPTER 3
ADJUSTMENTS2-Strokes - Edition 01 / 2023
95
3
A
B
1 2 3 4
8
5 76
D
N3EW
N3CW
C
A
B
N8RW
N3EW
N3CW
Jet needle adjustment (XX 250 version)
On the carburettor used in the XX250 the main nozzle is of
non-removable type and therefore cannot be replaced.
Therefore, adjusting the carburettor requires changing the
pin.
The pin adjustment parts, which have the same taper angle,
are available in different straight part diameters and different
taper start positions.
Standard pin: N3EW
If the retainer position number is the same, changing N3EW
to N3CW has the same effect as raising the retainer position
by 0.5.
A. Rich
B. Lean
C. Initial position of the taper part
D. 0.5 groove variation
Relationship with throttle opening (XX 250 version)
The flow of fuel through the main system of the carburettor
is controlled by the full jet and then further regulated by
the area between the atomizer and the taper pin. In the
relationship between fuel flow and throttle opening, fuel
flow refers to the diameter of the straight portion of the taper
pin around the 1/8 to 1/4 throttle opening, while the 1/4 to
1/1 throttle opening refers to the initial position of the taper
and the position of the clip.
Therefore, the fuel flow is balanced at each stage of the
throttle opening by a combination of the diameter of the
straight portion of the taper pin, the initial position of the
taper and the position of the clip.
A. Lean (larger diameter)
B. Rich (smaller diameter)
1. 1/8 throttle
2. 1/4 throttle
3. 1/2 throttle
4. Fully open
5. N3EW-3 pin
6. N3EJ-3 pin
7. N8RW-3 pin
8. Main nozzle
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