Yamaha YFZ450S 2003 Service Manual page 172

VALVES AND VALVE SPRINGS
4. Measure:
5. Measure:
NOTE:
_
• When installing a new valve always replace
• If the valve is removed or replaced always
6. Eliminate:
7. Check:
8. Measure:
4 - 29
• margin thickness a
Out of specification → Replace.
Margin thickness
Intake
1.0 mm (0.0394 in)
<Limit>: 0.85 mm (0.033 in)
Exhaust
1.0 mm (0.0394 in)
<Limit>: 0.85 mm (0.033 in)
• valve stem runout
Out of specification → Replace.
Valve stem runout
0.01 mm (0.0004 in)
the guide.
replace the oil seal.
• carbon deposits
(from the valve face and valve seat)
• valve seats
Pitting/wear → Reface the valve seat.
• valve seat width a
Out of specification → Reface the valve
seat.
Valve seat width
Intake
0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)
<Limit>: 1.6 mm (0.06 in)
Exhaust
0.9 ~ 1.1 mm
(0.0354 ~ 0.0433 in)
<Limit>: 1.6 mm (0.06 in)
ENG