Valve Seat Inspection/Refacing - Honda CRF450X 2005 Service Manual

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CYLINDER HEADIVALVES
Adjust the valve guide driver to the valve guide
height.
While the cylinder head is still heated, drive new
valve guides into the cyl i nder head from the top of
the cylinder (camshaft and rocker arm side).
Check that the valve guides are at the proper depth
using a cal iper. adjust the height if necessary.
SPECIFIED DEPTH:
IN: 16.1 - 16.3mm(O.63 - 0.64in)
EX: 17.9 - 18.1 mm (0.70 - 0.71 in)
TOOL:
Valve guide driver
07743·0020000
not available in
U.S.A.
Let the cyli nd er head cool to room temperature.
Use curringoiJon
Ream new valve guides.
the reamer during
Insert the reamer from the combustion chamber
this operation. side of the cyl inder head and always rotate the
Take care not
to
tilt
reamer clockwise.
or lean the reamer
In
the guide while
(eaming.
TOOLS:
IN: Valve guide reamer, 5.5 mm
EX: Valve guide reamer, 5.0 mm
07984-2000001 or
07984-2000000
(U .S.A. onlv)
07984-MA60001 or
07984· MA6000D
(U.S.A. onlv)
Clean the cyl i nder head thoroughly to remove any
metal particles after reaming and reface the valve
seats (page 9-30).
VALVE SEAT INSPECTION/REFACING
9-30
Clean the intake and exhaust valves thoroughly to
remove carbon deposits.
Apply light coati ng of Prussian Blue to the va lve
seat.
Tap the valves and seats using a rubber hose or
other hand·lapping tool.
Remove the valve and inspect the valve seat face.
The va lve seat contact should be w ithin the speci-
fied width and even all around the circumference.
STANDARD:
IN:
1.1 -
1.3 mm (0.04 - 0.05 in)
EX: 1.3 - 1.5 mm (0.05 - 0.06 in)
SERVICE LIMIT:
IN/ EX : 2.0 mm (0.08 in)
If the seat width is not within specification, reface
the valve seat (page 9-3 1).
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