Checking The Needle Valve; Checking The Throttle Valve; Checking The Jet Needle; Checking The Filter - Yamaha YZ125 2009 Owner's Service Manual

CHECKING THE NEEDLE VALVE

1. Inspect:
• Needle valve "1"
• Valve seat "2"
Grooved wear "a" → Replace.
Dust "b" → Clean.
Always replace the needle valve and valve seat
as a set.

CHECKING THE THROTTLE VALVE

1. Check:
• Free movement
Stick → Repair or replace.
Insert the throttle valve "1" into the carburetor
body, and check for free movement.

CHECKING THE JET NEEDLE

1. Inspect:
• Jet needle "1"
Bends/wear → Replace.
• Clip groove
Free play exists/wear → Replace.
• Clip position
Standard clip position:
No.3 Groove
CARBURETOR AND REED VALVE

CHECKING THE FILTER

1. Inspect:
• Filter "1"
Damage → Replace.
Inspect the filter as it is assembled to the carbu-
retor. Do not remove the filter except when re-
placing it.
MEASURING AND ADJUSTING THE FUEL
LEVEL
1. Measure:
• Fuel level "a"
Out of specification → Adjust.
Fuel level:
9.5–10.5 mm (0.37–0.41 in)
Above the float chamber mating
surface
Fuel level Measurement and adjustment
steps:
a. Remove the drain plug.
b. Connect the fuel level gauge adapter "2" and
fuel level gauge "1" to the float chamber.
Fuel level gauge adapter:
YM-01470/90890-01470
Fuel level gauge:
YM-1312-A/90890-01312
c. Hold the fuel level gauge vertically next to
the float chamber mating surface.
d. Measure the fuel level with the fuel level
gauge.
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