2017 YAMAHA WR 250F Owners Manual

Page 257 of 432

YAMAHA WR 250F 2017  Owners Manual VALVES AND VALVE SPRINGS
6-28
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a. Apply Mechanic’s blueing dye (Dykem) “b” 
onto the valve face.
b

Page 258 of 432

YAMAHA WR 250F 2017  Owners Manual VALVES AND VALVE SPRINGS
6-29
h. Install the valve into the cylinder head.
i. Press the valve through the valve guide and 
onto the valve seat to make a clear impres-
sion.
j. Measure the valve seat c

Page 259 of 432

YAMAHA WR 250F 2017  Owners Manual VALVES AND VALVE SPRINGS
6-30
EAS2GBB255INSTALLING THE VALVES
1. Clean:
• Valve stem end
2. Lubricate:
• Valve stem “1”
• Valve stem seal “2”
3. Install:
• Spring seat “1”
• Valv

Page 260 of 432

YAMAHA WR 250F 2017  Owners Manual VALVES AND VALVE SPRINGS
6-31
6. Lubricate:
• Adjusting pad “1”
• Valve lifter “2”
7. Install:
• Adjusting pad
• Valve lifter
TIP
• Check that the valve lifter turns smoothly 
when r

Page 261 of 432

YAMAHA WR 250F 2017  Owners Manual CYLINDER AND PISTON
6-32
EAS2GBB256
CYLINDER AND PISTON
Removing the cylinder and piston
Order Part name Q’ty Remarks
Cylinder headRefer to “CYLINDER HEAD” on page 6-20.
1Cylinder body
1
2Gasket

Page 262 of 432

YAMAHA WR 250F 2017  Owners Manual CYLINDER AND PISTON
6-33
EAS2GBB257REMOVING THE PISTON
1. Remove:
• Piston pin clip “1”
• Piston pin “2”
• Piston “3”
ECA
NOTICE
Do not use a hammer to drive the piston pin 
out.
TIP

Page 263 of 432

YAMAHA WR 250F 2017  Owners Manual CYLINDER AND PISTON
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b. If out of specification, rebore or replace the 
cylinder, and replace the piston and the pis-
ton rings as a set.
c. Measure the piston outside diameter “a” at 
the mea

Page 264 of 432

YAMAHA WR 250F 2017  Owners Manual CYLINDER AND PISTON
6-35
EAS2GBB260CHECKING THE PISTON PIN
1. Check:
• Piston pin
Blue discoloration/grooves  Replace the 
piston pin and then check the lubrication 
system.
2. Measure:
• Pisto