Valve Seat Check - Yamaha WaveRunner FX SHO Service Manual

POWR
Cylinder head

Valve seat check

1. Measure:
• Valve seat contact
Does not seat properly → Reface the
valve seat.
Measurement steps:
1. Eliminate carbon deposits from the valves
and valve seats.
2. Apply a thin, even layer of Mechanic's
blueing dye (Dykem) onto the valve seat.
3. Press the valve lightly against the valve
seat with a valve lapper (commercially
available).
4. Measure the valve seat contact width a
where the blueing dye is adhered to the
valve face. Reface the valve seat if the
valve is not seated properly or if the valve
seat contact width is out of specification.
Replace the valve guide if the valve seat
contact is uneven.
Valve seat contact width a:
Intake:
1.40–1.60 mm (0.055–0.063 in)
Exhaust:
1.50–1.70 mm (0.059–0.067 in)
5-74
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