Yamaha 2008 Raptor 250, Service Manual

Page: 134 / 311

ENG
4-18
CHECKING THE ROCKER ARMS AND
ROCKER ARM SHAFTS
The following procedure applies to all of the
rocker arms and rocker arm shafts.
1. Check:
• Rocker arms
• Valve clearance adjusting screws
Damage/wear
→
Replace.
2. Check:
• Rocker arm shaft
Blue discoloration/excessive wear/pitting/
scratches
→
Replace or check the lubrica-
tion system.
3. Measure:
• Rocker arm inside diameter
Out of specification
→
Replace.
4. Measure:
• Rocker arm shaft outside diameter
Out of specification
→
Replace.
5. Calculate:
• Rocker-arm-to-rocker-arm-shaft clearance
NOTE: NOTE:
Calculate the clearance by subtracting the
rocker arm shaft outside diameter from the
rocker arm inside diameter.
Out of specification
→
Replace the defec-
tive part(s).
Rocker arm inside diameter
12.000 ~ 12.018 mm
(0.4724 ~ 0.4731 in)
Limit
12.036 mm (0.4739 in)
Rocker arm shaft outside diameter
11.981 ~ 11.991 mm
(0.4717 ~ 0.4721 in)
Limit
11.950 mm (0.4705 in)
Rocker-arm-to-rocker-arm-shaft
clearance
0.009 ~ 0.037 mm
(0.0004 ~ 0.0015 in)
ROCKER ARM, CAMSHAFT