Honda NC700 2012, Service Manual

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CYLINDER HEAD/VALVES
VALVE SEAT REFACING
Follow the refacing
manufacturer's
operating
instructions.
Valve seat cutters/grinders or equivalent valve seat
refacing equipment are recommended to correct worn
valve seats.
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
irregularities from the seat.
Use a 32° cutter to remove the top 1/4 of the existing
valve seat material.
Use a 60° cutter to remove the bottom 1/4 of the old
seat.
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.
Reface the seat with
a 45° cutter
whenever a valve
guide is replaced.
TOOLS:
Seat cutter, 27.5 mm (45° IN)
07780-0010200
Seat cutter, 24 mm (45° EX) 07780-0010600
Cutter holder, 5.0 mm 07781-0010400
TOOLS:
Flat cutter, 28 mm (32° IN)
07780-0012100
Flat cutter, 25 mm (32° EX) 07780-0012000
Cutter holder, 5.0 mm 07781-0010400
TOOLS:
Interior cutter, 26 mm (60° IN)
07780-0014500
Interior cutter, 22 mm (60° EX) 07780-0014202
Cutter holder, 5.0 mm 07781-0010400
32°
60°
45°
[1]