Yamaha YZ125X 2023 Owner's Manual

ENGINE8-4EAM30605RELATIONSHIP WITH THROTTLE OPENINGThe flow of the fuel through the carburetor mainsystem is controlled by the main jet and then, itis further regulated by the area between themain 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 straightportion diameter around 1/8 to 1/4 throttle open-ing, whereas around 1/4 to 1/1 throttle opening itrelates to the taper starting position and to theclip position.Therefore, the fuel flow is balanced at eachstage of throttle opening by the combination ofthe jet needle straight portion diameter, taperstarting position and clip position.Example:EAM30599CARBURETOR SETTING PARTSA. Lean (larger diameter)B. Rich (smaller diameter)1. 1/8 throttle2. 1/4 throttle3. 1/2 throttle4. 1/1 throttlea. Main nozzle1NYCF-2NYCF-3NYCG-2NYDF-2Part name Size Part numberMain jet Rich #175 4MX-14943-42#172 4MX-14943-92#170 4MX-14943-41#168 4MX-14943-91#165 4MX-14943-40*(STD) #162 4MX-14943-90(STD) #160 4MX-14943-39#158 4MX-14943-89#155 4MX-14943-38#152 4MX-14943-88#150 4MX-14943-37Lean #148 4MX-14943-87Pilot jet Rich #80 B4X-14948-19#78 B4X-14948-18#75 B4X-14948-17#72 B4X-14948-16#70 B4X-14948-15#68 B4X-14948-14(STD) #65 B4X-14948-13#62 4MX-14948-12*(STD) #60 4MX-14948-11#58 4MX-14948-10#55 4MX-14948-09#52 4MX-14948-08Lean #50 4MX-14948-07