Yamaha YZ250F(S) Owner's Service Manual page 278

CARBURETOR
Float height
1. Measure:
Float height a
G
Out of specification → Adjust.
Float height:
8.0 mm (0.31 in)
Measurement and adjustment steps:
Hold the carburetor in an upside down
G
position.
NOTE:
Slowly tilt the carburetor in the opposite
G
direction, then take the measurement
when the needle valve aligns with the float
arm.
If the carburetor is level, the weight of the
G
float will push in the needle valve, result-
ing in an incorrect measurement.
Measure the distance between the mating
G
surface of the float chamber and top of the
float using a vernier calipers.
NOTE:
The float arm should be resting on the nee-
dle valve, but not compressing the needle
valve.
If the float height is not within specifica-
G
tion, inspect the valve seat and needle
valve.
If either is worn, replace them both.
G
If both are fine, adjust the float height by
G
bending the float tab b on the float.
Recheck the float height.
G
EC464600
Float
1. Inspect:
Float 1
G
Damage → Replace.
4 - 13
ENG