Yamaha WR400F 1999 Manual De Servicio página 328

VALVES AND VALVE SPRINGS
NOTE:
After replacing the valve guide reface the
valve seat.
3. Inspect:
4. Measure:
5. Measure:
NOTE:
When installing a new valve always replace
the guide.
If the valve is removed or replaced always
replace the oil seal.
6. Eliminate:
7. Inspect:
8. Measure:
4 - 33
Valve face
Pitting/wear → Grind the face.
Valve stem end
Mushroom shape or diameter larger
than the body of the stem → Replace.
Margin thickness a
Out of specification → Replace.
Margin thickness:
Intake:
1.0 mm (0.039 in)
<Limit>: 0.85 mm (0.033 in)
Exhaust:
1.0 mm (0.039 in)
<Limit>: 0.85 mm (0.033 in)
Runout (valve stem)
Out of specification → Replace.
Runout limit:
0.01 mm (0.0004 in)
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>: 1.5 mm (0.06 in)
Exhaust:
0.9 ~ 1.1 mm (0.0354 ~ 0.0433 in)
<Limit>: 1.5 mm (0.06 in)
ENG