Checking The Rocker Arms And Rocker Arm; Shafts - Yamaha YFM250RX 2008 Service Manual

ROCKER ARM, CAMSHAFT
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.
Rocker arm inside diameter
Limit
4. Measure:
• Rocker arm shaft outside diameter
Out of specification → Replace.
Rocker arm shaft outside diameter
Limit
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-to-rocker-arm-shaft
clearance
4-18
ENG
12.000 ~ 12.018 mm
(0.4724 ~ 0.4731 in)
12.036 mm (0.4739 in)
11.981 ~ 11.991 mm
(0.4717 ~ 0.4721 in)
11.950 mm (0.4705 in)
0.009 ~ 0.037 mm
(0.0004 ~ 0.0015 in)