Yamaha YZ125(T)/T1 Owner's Service Manual page 512

SETTING
EC714060
Effect of setting parts in relation to throttle
valve opening
Setting part
Pilot air screw
Pilot jet
Diameter of
straight portion
Clip position
Throttle valve
Main jet
1 Throttle valve opening
2 Full-open
3 Full-closed
EC715002
Main jet adjustment
The richness of air-fuel mixture with 1/2~4/4
throttle can be set by changing the main jet 1.
Standard main jet
*For EUROPE
1. Spark plug is too hot.
Select a main jet having higher calibrating
No. than standard. (To be enriched)
2. Spark plug is wet.
Select a main jet having lower calibrating No.
than standard. (To be leaned out)
7-3
TUN
Throttle valve opening
Full-closed 1/4 1/2 3/4 Full-open
#410
*#430