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VALVE SEAT WIDTH
• Coat the valve seat uniformly with Prussian blue. Fit the
valve and tap the coated seat with the valve face in a
rotating manner, in order to obtain a clear impression of
the seating contact. In this operation, use the valve lap-
per to hold the valve head.
• The ring-like dye impression left on the valve face must
be continuous-without any break. In addition, the width
of the dye ring, which is the visualized seat "width", must
be within the specification.
Standard
Valve seat width
@:
0.9-1.1 mm (0.035-0.043 in)
If either requirement is not met, correct the seat by servic-
ing it as follows.
VALVE SEAT SERVICING
The valve seats for both intake and exhaust valves are
machined to two different angles. (The seat contact surface
is cut 45°.)
----
INTAKE
EXHAUST
45°
N-615
N-615
15°
N-615
N-121
(For U.S.A.)
Valve seat cutter (N-615)
Valve seat cutter (N-121)
Solid pilot (N-140-7.0)
(For the Others)
S
09916-24900: Valve seat cutter set
09916-20610: Valve seat cutter (N-121)
09916-24210: Valve seat cutter (N-615)
(N-140-7.0)
: Solid pilot
NOTE:
The vlave seat contact area must be inspected after each
cut.
• Insert the solid pilot with a slight rotation, seat the pilot
snugly. Install the 45° cutter and T-handle.
• Using the 45° cutter, descale and clean up the seat with
one or two turns.
• Inspect the seat by the previously described seat width
measurement procedure. If the seat is pitted or burned,
additional seat conditioning with the 45 ° cutter is re-
quired.
NOTE:
Cut the minimum amount necessary from the seat to pre-
vent the possibility of the valve stem becoming too close
to the rocker arm for correct valve contact angle.
ENGINE 3-22
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