Valve Seat Inspection/Refacing - Honda CRF1000 Shop Manual

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CYLINDER HEAD/VALVE/CAMSHAFT

VALVE SEAT INSPECTION/REFACING

Disassemble the cylinder head (page 10-14).
Clean the intake and exhaust valves thoroughly to
remove carbon deposits.
Apply a light coating of Prussian Blue to the valve
seats.
Tap the valves and seats using a rubber hose or other
hand-lapping tool [1].
Measure the valve seat width according to CYLINDER
HEAD/VALVE/CAMSHAFT SPECIFICATIONS (page
1-7).
Inspect the valve seat face for:
The valves cannot
be ground. If the
• Uneven seat width:
valve face is
– replace the valve and reface the valve seat.
burned, badly worn,
• Damaged face:
or if it contacts the
– replace the valve and reface the valve seat.
seat unevenly,
• Contact area (too high or too low)
replace the valve.
– reface the valve seat.
REFACING
Reface the valve seat using the following tools.
TOOLS:
Cutter holder, 5.5 mm
Seat cutter, 40 mm (45° IN)
Seat cutter, 35 mm (45° EX)
Flat cutter, 42 mm (32° IN/EX)
Interior cutter, 34 mm (60° IN/EX) 07780-0014700
STANDARD:
IN: 1.1 – 1.3 mm (0.04 – 0.05 in)
EX: 1.3 – 1.5 mm (0.05 – 0.06 in)
SERVICE LIMITS:
IN: 1.5 mm (0.06 in)
EX: 1.9 mm (0.07 in)
• Follow
instructions.
• Be careful not to grind the seat more than
necessary.
1. Use a 45° seat cutter, remove any roughness or
irregularities from the seat.
2. Use a 32° flat cutter, remove the top 1/4 of the
existing valve seat material.
3. Use a 60° interior cutter, remove the bottom 1/4 of
the existing valve seat material.
4. Using a 45° seat cutter, cut the seat to the proper
width.
Make sure that all pitting and irregularities are
removed.
5. 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 any residual compound off the
cylinder head and valve and recheck the seat contact.
Assemble the cylinder head (page 10-17).
10-16
07781-0010101
07780-0010500
07780-0010400
07780-0013000
the refacer manufacturer's
[1]
operating
[1]
Old seat width
32°
Old seat width
60°