Yamaha F350B - Refacing the Valve Seat

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Cylinder head
c. Measure the valve seat contact width “a”
where the blue layout fluid is adhered to
the valve face.
TIP:
• Reface the valve seat if the valve is not seat-
ed properly or if the valve seat contact width
is out of specification.
• Check the valve guide if the valve seat con-
tact width is uneven.
Refacing the valve seat
After every lapping procedure, make sure
to clean off any remaining lapping com-
pound from the cylinder head and valves.
1. Reface:
• Valve seat
a. Reface the valve seat using the special
service tools.
Seat contact width IN
1.10–1.40 mm (0.0433–0.0551
in)
Limit
1.850 mm (0.0728 in)
Seat contact width EX
1.40–1.70 mm (0.0551–0.0669
in)
Limit
2.150 mm (0.0846 in)
a
Valve seat cutter holder
90890-06316
Intake:
Valve seat cutter 30deg-42mm
90890-06464
Valve seat cutter 45
90890-06332
Valve seat cutter 65deg-40mm
90890-06465
Exhaust:
Valve seat cutter 30
90890-06327
Valve seat cutter 45
90890-06325
Valve seat cutter 60
90890-06324
Neway valve seat kit
YB-91044
60 65
4530