Honda NC700XA Service Manual page 330

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VALVE SEAT REFACING
Valve seat cutters/grinders or equivalent valve seat
Follow the refacing
refacing equipment are recommended to correct worn
manufacturer's
valve seats.
operating
instructions.
If the contact area is too high on the valve, the seat
must be lowered using a 32° flat cutter.
If the contact area is too low on the valve, the seat must
be raised using a 60° interior cutter.
Refinish the seat to specifications, using a 45° finish
cutter.
Use a 45° cutter to remove any roughness or
Reface the seat with
irregularities from the seat.
a 45° cutter
whenever a valve
TOOLS:
guide is replaced.
Seat cutter, 27.5 mm (45° IN)
Seat cutter, 24 mm (45° EX)
Cutter holder, 5.0 mm
Use a 32° cutter to remove the top 1/4 of the existing
valve seat material.
TOOLS:
Flat cutter, 28 mm (32° IN)
Flat cutter, 25 mm (32° EX)
Cutter holder, 5.0 mm
Use a 60° cutter to remove the bottom 1/4 of the old
seat.
TOOLS:
Interior cutter, 26 mm (60° IN)
Interior cutter, 22 mm (60° EX)
Cutter holder, 5.0 mm
Using a 45° seat cutter, cut the seat to the proper width.
Make sure that all pitting and irregularities are removed.
Refinish if necessary.
After cutting the seat, apply lapping compound to the
valve face, and lap the valve using light pressure.
• Excessive lapping pressure may deform or damage
the seat.
• Change the angle of lapping tool [1] frequently to
prevent uneven seat wear.
• Do not allow lapping compound to enter the guides.
After lapping, wash all residual compound off the
cylinder head and valve.
Recheck the seat contact after lapping.
07780-0010200
07780-0010600
07781-0010400
07780-0012100
07780-0012000
07781-0010400
07780-0014500
07780-0014202
07781-0010400
CYLINDER HEAD/VALVES
45°
32°
10-23
60°
[1]