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Yamaha yz250 2015 User Manual

Yamaha yz250 2015
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3-20
ELECTRICAL
ELECTRICAL
CHECKING THE SPARK PLUG
1. Remove:
Spark plug
2. Inspect:
Electrode "1"
Wear/damage Replace.
Insulator color "2"
Normal condition is a medium to
light tan color.
Distinctly different color Check
the engine condition.
When the engine runs for many hours
at low speeds, the spark plug insula-
tor will become sooty, even if the en-
gine and carburetor are in good
operating condition.
3. Measure:
Plug gap "a"
Use a wire gauge or thickness
gauge.
Out of specification Regap.
4. Clean the plug with a spark plug
cleaner if necessary.
5. Tighten:
Spark plug
Before installing a spark plug, clean
the gasket surface and plug sur-
face.
Finger-tighten "a" the spark plug
before torquing to specification "b".
CHECKING THE IGNITION TIMING
1. Remove:
•Fuel tank
Refer to "SEAT, FUEL TANK
AND SIDE COVERS" section in
the CHAPTER 4.
Spark plug
Crankcase cover (left)
2. Attach:
Dial gauge "1"
Spark plug hole dial stand "2"
3. Rotate the magneto rotor "1" until
the piston reaches top dead cen-
ter (TDC). When this happens,
the needle on the dial gauge will
stop and reverse directions even
though the rotor is being turned in
the same direction.
4. Set the dial gauge to zero at TDC.
5. From TDC, rotate the rotor clock-
wise until the dial gauge indicates
that the piston is at a specified
distance from TDC.
6. Check:
Ignition timing
Punch mark "a" on rotor should be
aligned with punch mark "b" on
stator.
Not aligned Adjust.
7. Adjust:
Ignition timing
Adjustment steps:
a. Loosen the screws (stator) "1".
b. Align the punch mark on the rotor
with punch mark on the stator "2"
by moving the stator.
c. Tighten the screws (stator).
Spark plug gap "a":
0.5–0.6 mm (0.020–
0.024 in)
Standard spark plug:
BR8EG/NGK (resistance type)
Spark plug:
20 Nm (2.0 m•kg, 14
ft•lb)
Dial gauge:
YU-03097-B/90890-
01252
Spark plug hole dial
stand:
YU-01256
Ignition timing (B.T.D.C.):
0.18 mm (0.007 in)
Screw (stator):
7 Nm (0.7 m•kg, 5.1
ft•lb)

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Yamaha yz250 2015 Specifications

General IconGeneral
Displacement249cc
Bore x Stroke66.4mm x 72.0mm
Compression Ratio8.9~10.6:1
IgnitionCDI
Transmission5-speed; multiplate wet clutch
Final DriveChain
Front Tire80/100-21
Rear Tire110/90-19
Wheelbase58.3 in
Seat Height39.1 in
Ground Clearance14.2 in
Fuel Capacity2.1 gal
Wet Weight227 lbs
Engine Type2-stroke
Fuel SystemKeihin PWK38S
Front SuspensionKYB Speed-Sensitive System inverted fork; fully adjustable
Rear Suspension12.4-in travel
Front BrakeSingle disc, 250mm
Rear BrakeHydraulic single disc brake, 245mm
Width32.5 inches

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