SETTING

T U N

1 Jet needle

2 Pilot air jet

3 Needle jet

4 Main jet

5 Pilot jet

6 Pilot screw

Main jet adjustment

The richness of the air-fuel mixture at full throt- tle can be set by changing the main jet 1.

Standard main jet

#185

* #172

* Except for USA

If the air-fuel mixture is too rich or too lean, the engine power will drop, resulting in poor accel- eration.

Effects of changing the main jet (reference)

È

1/4

1/2

3/4

#195

#175

ÈIdle

ÉFully open

É

+10%

#185

–10%

7 - 4

Page 324
Image 324
Yamaha WR250FM service manual Main jet adjustment, Standard main jet #185 #172, Effects of changing the main jet reference