![Yamaha 2000 WR450F Owner'S Service Manual Download Page 328](http://html.mh-extra.com/html/yamaha/2000-wr450f/2000-wr450f_owners-service-manual_899346328.webp)
4 - 33
ENG
VALVES AND VALVE SPRINGS
3. Inspect:
●
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.
5. Measure:
●
Runout (valve stem)
Out of specification
→
Replace.
NOTE:
●
When installing a new valve always replace
the guide.
●
If the valve is removed or replaced always
replace the oil seal.
6. Eliminate:
●
Carbon deposits
From the valve face and valve seat.
7. Inspect:
●
Valve seats
Pitting/wear
→
Reface the valve seat.
8. Measure:
●
Valve seat width
a
Out of specification
→
Reface the valve
seat.
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 limit:
0.01 mm (0.0004 in)
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)
NOTE:
After replacing the valve guide reface the
valve seat.