Relationship With Throttle Opening; Carburetor Setting Parts - Yamaha YZ125X 2023 Owner's Manual

EAM30605

RELATIONSHIP WITH THROTTLE OPENING

The flow of the fuel through the carburetor main
system is controlled by the main jet and then, it
is further regulated by the area between the
main nozzle and the jet needle. On the relation-
ship between the fuel flow and the throttle open-
ing, the fuel flow relates to the jet needle straight
portion diameter around 1/8 to 1/4 throttle open-
ing, whereas around 1/4 to 1/1 throttle opening it
relates to the taper starting position and to the
clip position.
Therefore, the fuel flow is balanced at each
stage of throttle opening by the combination of
the jet needle straight portion diameter, taper
starting position and clip position.
Example:
NYCF-2
NYCF-3
A. Lean (larger diameter)
B. Rich (smaller diameter)
1. 1/8 throttle
2. 1/4 throttle
3. 1/2 throttle
4. 1/1 throttle
a. Main nozzle
1
NYCG-2
NYDF-2
8-4
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CARBURETOR SETTING PARTS

Part name
Main jet Rich
*(STD)
(STD)
Lean
Pilot jet Rich
(STD)
*(STD)
Lean
ENGINE
Size Part number
#175 4MX-14943-42
#172 4MX-14943-92
#170 4MX-14943-41
#168 4MX-14943-91
#165 4MX-14943-40
#162 4MX-14943-90
#160 4MX-14943-39
#158 4MX-14943-89
#155 4MX-14943-38
#152 4MX-14943-88
#150 4MX-14943-37
#148 4MX-14943-87
#80 B4X-14948-19
#78 B4X-14948-18
#75 B4X-14948-17
#72 B4X-14948-16
#70 B4X-14948-15
#68 B4X-14948-14
#65 B4X-14948-13
#62 4MX-14948-12
#60 4MX-14948-11
#58 4MX-14948-10
#55 4MX-14948-09
#52 4MX-14948-08
#50 4MX-14948-07