Honda WB20XT2 Manual page 109

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CYLINDER HEAD
Check the valve guide bore; it should be straight, round,
and centered in the valve guide. Insert the valve and
check operation. If the valve does not operate
smoothly, the guide may have been bent during
installation.
Replace the valve guide if it is bent or damaged (page
12-8).
Check the valve guide-to-stem clearance (page 12-7).
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 31° flat cutter.
Valve seat cutter (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 (Commercially available):
Valve seat cutter, 31°
Valve seat cutter, 45°
Valve seat cutter, 60°
Solid pilot (short) 5.5 mm
Accessory kit
T-wrench
Adapter, 1/2"-3/8"
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:
WB20XT2:
IN/EX: 0.70 – 0.90 mm (0.028 – 0.035 in)
WB30XT2:
IN:
EX:
12-10
NWYCU115
NWYCU122
MWYCU111
NWYPM10055SH
NWYKACC246
NWYTW505
NWYTW503-1
0.70 – 0.90 mm (0.028 – 0.035 in)
0.90 – 1.10 mm (0.035 – 0.043 in)
WB20XT2•WB30XT2
45°
TOO LOW
60°
TOO HIGH
31°
45°
(1)