Honda GP160H Manual page 96

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VALVE SEAT RECONDITIONING
Inspect the valve seat contact area (page 12-6).
Using a 45° seat cutter, remove any roughness or
irregularities from the seat.
If the contact area is too low on the valve, the seat must
be raised using a 60° interior cutter.
If the contact area is too high on the valve, the seat
must be lowered using a 32° flat cutter.
Valve seat cutters [1]/grinder or equivalent valve seat
refacing equipment is recommended to correct a worn
valve seat.
• Turn the cutter clockwise, never counterclockwise.
• Continue to turn the cutter as you lift it from the valve
seat.
TOOLS:
Cutter holder, 5.5 mm [2]
Seat cutter, 27.5 mm (45° IN)
Seat cutter, 24.5 mm (45° EX)
Flat cutter, 28 mm (32° IN)
Flat cutter, 24 mm (32° EX)
Interior cutter, 26 mm (60° IN)
Interior cutter, 22 mm (60° EX)
Make a light pass with the 45° cutter to remove any
possible burrs at the edge of the seat.
Be sure that the width of the finished valve seat is within
specification.
STANDARD: 0.70 – 0.90 mm (0.028 – 0.035 in)
Lap the valves into their seats, using a commercially
available valve lapper and lapping compound.
After lapping, wash all residual compound off the
cylinder head and valve.
• Do not push the valve against the seat with force
during lapping. Apply a light pass with the valve
lapper.
• Avoid lapping the valve in the same position as it
causes uneven wear. Lap the valve by turning the
lapper slowly.
• Take care not to allow the lapping compound to
enter the gap between the stem and guide.
07781-0010101
07780-0010200
07780-0010100
07780-0012100
07780-0012500
07780-0014500
07780-0014202
CYLINDER HEAD
45°
TOO LOW
60°
TOO HIGH
32°
45°
VALVE LAPPER
(Commercially available)
12-9
[2]
[1]