Yamaha YZ125 2009 User Manual

4-12
CARBURETOR AND REED VALVE
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
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 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.
c. Hold the fuel level gauge vertically next to
the float chamber mating surface.
d. Measure the fuel level with the fuel level
gauge.
Standard clip position:
No.3 Groove
Fuel level:
9.5–10.5 mm (0.37–0.41 in)
Above the float chamber mating
surface
Fuel level gauge adapter:
YM-01470/90890-01470
Fuel level gauge:
YM-1312-A/90890-01312

Yamaha YZ125 2009 Specifications

General

Engine Type	124cc liquid-cooled 2-stroke; reed-valve inducted
Bore x Stroke	54.0mm x 54.5mm
Compression Ratio	8.6~10.7:1
Ignition	CDI
Final Drive	Chain
Front Brake	Hydraulic single disc brake, 250mm
Rear Brake	Hydraulic single disc brake, 245mm
Front Tire	80/100-21
Rear Tire	100/90-19
Overall Width	32.5 in
Wheelbase	58.3 in
Fuel Capacity	2.1 gal
Wet Weight	207 lb
Dry Weight	194 lb
Fuel Delivery	Mikuni® TMX 38
Front Suspension	Speed-sensitive inverted fork; fully adjustable, 11.8 in travel
Rear Suspension	Fully adjustable, 12.4-in travel