Checking The Valve Seats - Yamaha WR450FB 2012 Owner's Service Manual

TIP_·~~~~~---'"~~~~~~~~
After replacing the valve guide, reface the valve
seat.
Intake
Valve guide rert:Jover (04.5)
90890-04116
VM-04116
Valve guide installer (04.5)
90890-04117
VM-04117
Valve guide reamer (04.5)
90890-04118
VM-04118
Exhaust
Valve guide remover{05.0)
90890-()4097
. VM-04097
Valve guide installer (05.0)
90890-04098
VM-04098
Valve guide reamer (05.0)
90890-04099
VM-04099
••••••••••••••••••••••••••••••••
3. Eliminate: ·
• Carbon deposits
(from the valve face and valve seat)
4. Check:
•Valve face
Pitting/wear
~
Grind the valve face.
• Valve stem end
Mushroom shape or diarneter larger than
the body of the valve stem
~
Replace the
valve.
5. Measure:
•Valve margin thickness "a"
Out of
specification~
Replace the valve.
Valve margin thickness D (intake)
1.00 mm (0.0394 in)
Valve margin thickness D (ex-
haust)
1.00 mm (0.0394 in)
VALVES AND VALVE SPRINGS
6-21
a-JI-
i j rn
J
-----
~45°
6. Measure:
•Valve stem runout
Out of specification
~
Replace tlie valve.
TIP~~~~~~~~~~~~~~-
• When installing a new valve, always replace
the valve guide.
• If the valve is removed or replaced, always re-
place the oil seal. .
EAS24300
Valve stem· runout
0.010 mm (0.0004 in)
CHECKING THE VALVE SEATS
/ /
The following procedure applies to all of the
valves and valve seats.
1. Eliminate:
• Carbon deposits
(from the valve face and valve seat)
2. Check:
•Valve seat
Pitting/wear
~
Replace the cylinder head.
3. Measure:
•Valve seat width "a"
Out of
specification~
Replace the cylinder
head.
Valve seat width C (intake)
0.90-1.10 mm (0.0354-0.0433 in)
Valve seat width C (exhaust)
0.90-1.1
o
mm (0.0354-0.0433 in)