Jet Needle; Float Height - Yamaha TT-R90(P) Owner's Service Manual

CARBURETOR
EC464401

Jet needle

1. Inspect:
Jet needle 1
Bends/wear
Clip groove
Free play exists/wear
Clip position
Standard clip position:
No.2 Groove

Float height

1. Measure:
Float height a
Out of specification
Float height:
15.5 ~ 16.5 mm (0.61 ~ 0.65 in)
Measurement and adjustment steps:
Hold the carburetor in an upside down
position.
NOTE:
Slowly tilt the carburetor in the opposite
direction, then take the measurement
when the needle valve aligns with the float
arm.
If the carburetor is level, the weight of the
float will push in the needle valve, result-
ing in an incorrect measurement.
Measure the distance between the mating
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-
tion, inspect the valve seat and needle
valve.
If either is worn, replace them both.
If both are fine, adjust the float height by
bending the float tab 1 on the float.
Recheck the float height.
4 - 5
ENG
Replace.
Replace.
Adjust.