Checking The Rocker Arms And Rocker Arm Shafts - Yamaha 2009 YFM25RY Service Manual

4. Check:
• Camshaft oil passage
Obstruction → Blow out with compressed
air.
EAS23880
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 "1"
• Valve clearance adjusting screws "2"
Damage/wear → Replace.
2. Check:
• Rocker arm shaft
Blue discoloration/excessive wear/pitting/
scratches → Replace or check the lubri-
cation system.
3. Measure:
• Rocker arm inside diameter "a"
Out of specification → Replace.
Rocker arm inside diameter
12.000–12.018 mm (0.4724–
0.4731 in)
Limit
12.036 mm (0.4739 in)
4. Measure:
• Rocker arm shaft outside diameter "a"
Out of specification → Replace.
Rocker arm shaft outside diam-
eter
11.981–11.991 mm (0.4717–
0.4721 in)
Limit
11.950 mm (0.4705 in)
5. Calculate:
• Rocker-arm-to-rocker-arm-shaft clear-
ance
TIP
Calculate the clearance by subtracting the
rocker arm shaft outside diameter from the
rocker arm inside diameter.
5-8
CAMSHAFT