Yamaha Rhino 450 YXR45FAV Service Manual page 154

CAMSHAFT, ROCKER ARMS AND VALVES
3. Check:
• valve face
Pitting/wear → Grind the face.
• valve stem end
Mushroom shape or diameter larger than
the body of the stem → Replace.
4. Measure:
• margin thickness a
Out of specification → Replace.
Margin thickness
Intake
1.0 ~ 1.4 mm (0.0394 ~ 0.0551 in)
Exhaust
0.8 ~ 1.2 mm (0.0315 ~ 0.0472 in)
5. Measure:
• valve stem runout
Out of specification → Replace.
Runout limit
0.01 mm (0.0004 in)
NOTE:
• When installing a new valve, always replace
the guide.
• If the valve is removed or replaced, always
replace the valve stem seal.
6. Eliminate:
• carbon deposits
(from the valve face and valve seat)
7. Check:
• valve seats
Pitting/wear → Reface the valve seat.
8. Measure:
• valve seat width a
Out of specification → Reface the valve
seat.
Valve seat width
Intake
1.2 ~ 1.4 mm (0.0472 ~ 0.0551 in)
<Limit>: 1.6 mm (0.0630 in)
Exhaust
1.2 ~ 1.4 mm (0.0472 ~ 0.0551 in)
<Limit>: 1.6 mm (0.0630 in)
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ENG