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Yamaha YZ250FX 2019 User Manual

Yamaha YZ250FX 2019
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ENGINE
3-16
TIP
Get the high tension cord “1” of the ignition coil
pinched in the detector “a” of the digital tachom-
eter.
4. Measure:
Engine idling speed
Out of specification Regulate.
5. Adjust:
Engine idling speed
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the starter knob/idle screw “1” in the di-
rection of “a” or “b” to make an adjustment.
▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲▲
EAM30226
ADJUSTING THE VALVE CLEARANCE
TIP
This section is intended for those who have ba-
sic knowledge and skill concerning the servic-
ing of Yamaha motorcycles (e.g., Yamaha
dealers, service engineers, etc.). Those who
have little knowledge and skill concerning ser-
vicing are requested not to undertake inspec-
tion, adjustment, disassembly, or reassembly
only by reference to this manual. It may lead to
servicing trouble and mechanical damage.
Make sure that the valve clearance is checked
or adjusted while the engine is cold (at room
temperature).
While the valve clearance is checked or adjust-
ed, make sure that the piston is positioned in
the top dead center (TDC).
1. Remove:
Seat
Side cover (left/right)
Air scoop (left/right)
Refer to “GENERAL CHASSIS” on page 4-1.
Fuel tank
Refer to “FUEL TANK” on page 7-1.
ECU
2. Remove:
Spark plug
Cylinder head cover
Refer to “CAMSHAFT” on page 5-11.
3. Remove:
Timing mark accessing screw “1”
Crankshaft end accessing screw “2”
O-ring
4. Check:
Valve clearance
Out of specification Regulate.
▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼▼
a. Turn the crankshaft counterclockwise with a
wrench.
Digital tachometer
90890-06760
Digital tachometer
YU-39951-B
Engine idling speed
1900–2100 r/min
Direction “a”
Engine idling speed
Decreases.
Direction “b”
Engine idling speed
Increases.
1
1
a
a
1
b
a
Valve clearance (cold)
Intake
0.12–0.19 mm (0.0047–0.0075 in)
Exhaust
0.17–0.24 mm (0.0067–0.0094 in)
1
2

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Yamaha YZ250FX 2019 Specifications

General IconGeneral
Displacement250cc
Bore x Stroke77.0mm x 53.6mm
Fuel SystemYamaha Fuel Injection (YFI), Keihin® 44mm
IgnitionTCI: Transistor Controlled Ignition
Final DriveChain
Front BrakeHydraulic disc, 270mm
Rear BrakeHydraulic disc, 245mm
Seat Height37.6 in
Ground Clearance12.8 in
Fuel Capacity2.1 gal
Wet Weight249 lb
Engine TypeLiquid-cooled DOHC 4-stroke
TransmissionWide-ratio 6-speed; multiplate wet clutch
Front SuspensionKYB® spring-type fork, fully adjustable
Rear SuspensionKYB® single shock
L x W x H32.5 in
Front Tire90/90-21
Rear Tire110/100-18

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