ENGINE
3-6
EAM20135
ENGINE
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 5-14.
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.
b. Align the top dead center (TDC) mark “a”
on the generator rotor with the alignment
mark “b” on the crankcase cover.
TIP
Check that the alignment mark “c” on the cam-
shaft sprocket and the alignment mark “d” on the
intake camshaft sprocket are aligned with the
edge of the cylinder head.
c. Measure the valve clearance using a
thickness gauge “1”.
TIP
Record the measured reading if the clearance is
incorrect.
1
2
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)
Thickness gauge
90890-03268
Feeler gauge set
YU-26900-9
b
a
d
c
Summary of Contents for YZ250FX 2021
Page 6: ...EAM20162 YAMAHA MOTOR CORPORATION U S A YZ MOTORCYCLE LIMITED WARRANTY ...
Page 10: ......
Page 61: ...TIGHTENING TORQUES 2 16 ...
Page 62: ...CABLE ROUTING DIAGRAM 2 17 EAM20152 CABLE ROUTING DIAGRAM Frame and engine left side view ...
Page 64: ...CABLE ROUTING DIAGRAM 2 19 Frame and engine right side view ...
Page 66: ...CABLE ROUTING DIAGRAM 2 21 Handlebar front view ...
Page 68: ...CABLE ROUTING DIAGRAM 2 23 Frame and engine top view ...
Page 70: ...CABLE ROUTING DIAGRAM 2 25 Frame and battery top view ...
Page 72: ...CABLE ROUTING DIAGRAM 2 27 Rear brake right side view ...
Page 74: ...CABLE ROUTING DIAGRAM 2 29 ...
Page 112: ...ELECTRICAL SYSTEM 3 36 ...
Page 153: ...HANDLEBAR 4 39 Throttle grip free play 3 0 6 0 mm 0 12 0 24 in ...
Page 166: ...FRONT FORK 4 52 1 ...
Page 184: ...CHAIN DRIVE 4 70 ...
Page 189: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 5 3 1 Oil filter element 2 Oil pump ...
Page 190: ...LUBRICATION SYSTEM CHART AND DIAGRAMS 5 4 1 Intake camshaft 2 Exhaust camshaft ...
Page 264: ...TRANSMISSION 5 78 ...
Page 274: ...WATER PUMP 6 9 ...
Page 284: ...THROTTLE BODY 7 9 ...
Page 287: ......
Page 288: ...IGNITION SYSTEM 8 1 EAM20142 IGNITION SYSTEM EAM30277 CIRCUIT DIAGRAM ...
Page 292: ...ELECTRIC STARTING SYSTEM 8 5 EAM20143 ELECTRIC STARTING SYSTEM EAM30279 CIRCUIT DIAGRAM ...
Page 296: ...CHARGING SYSTEM 8 9 EAM20144 CHARGING SYSTEM EAM30282 CIRCUIT DIAGRAM ...
Page 299: ...CHARGING SYSTEM 8 12 ...
Page 300: ...SIGNALING SYSTEM 8 13 EAM20154 SIGNALING SYSTEM EAM30348 CIRCUIT DIAGRAM ...
Page 304: ...FUEL INJECTION SYSTEM 8 17 EAM20145 FUEL INJECTION SYSTEM EAM30284 CIRCUIT DIAGRAM ...
Page 329: ...FUEL INJECTION SYSTEM 8 42 ...
Page 330: ...FUEL PUMP SYSTEM 8 43 EAM20146 FUEL PUMP SYSTEM EAM30287 CIRCUIT DIAGRAM ...
Page 362: ...SELF DIAGNOSTIC FUNCTION AND DIAGNOSTIC CODE TABLE 9 15 ...
Page 372: ...CHASSIS 10 9 ...
Page 374: ......
Page 376: ......
Page 377: ...YZ250FXM 2021 WIRING DIAGRAM BAJ 2819U 11_WD indd 1 2020 06 29 15 46 05 ...
Page 378: ...YZ250FXM 2021 WIRING DIAGRAM BAJ 2819U 11_WD indd 2 2020 06 29 15 46 06 ...