Valve Guide Replacement; Valve/Valve Guide - Honda TRX450R Service Manual

CYLINDER HEAD/VALVE
VALVE/VALVE GUIDE
Check that the valve moves smoothly in the guide.
Check the valve for bending, burning or abnormal
wear.
Measure each valve stem O.D. and record it.
SERVICE LIMITS: IN: 5.46 mm (0.215 in)
EX: '04 - '05;
5.44 mm (0.214 in)
After '05;
4.96 mm (0.195 in)
Ream the guides to remove any carbon build-up
before measuring the guide.
Insert the reamer from the combustion chamber
side of the head and always rotate the reamer clock-
wise.
TOOL:
Valve guide reamer, 5.5 mm
After '05; EX:
Valve guide reamer, 5.0 mm
07984-2000001 or
07984-200000D
(U.S.A. only)
07984-MA60001 or
07984-MA6000D
(U.S.A. only)
Measure each valve guide I.D. and record it.
SERVICE LIMIT: IN/EX: 5.52 mm (0.217 in)
After 05; EX:
SERVICE LIMIT: 5.052 mm (0.1989 in)
Subtract each valve stem O.D. from the correspond-
ing guide I.D. to obtain the stem-to-guide clearance.
SERVICE LIMITS: IN: 0.12 mm (0.005 in)
EX: 04 - '05;
0.14 mm (0.006 in)
After '05;
0.13 mm (0.005 in)
If the stem-to-guide clearance exceeds the service
limit, determine if a new guide with standard
whenever the valve dimensions would bring the clearance within toler-
gutdes are replaced ance. If so, replace any guides as necessary and
ream to fit.
If the stem-to-guide clearance exceeds the service
limit with a new guide, also replace the valve.
Inspect and reface
the valve seats
(page 11-20).
VALVE GUIDE REPLACEMENT
Mark new valve guides at the specified height indi-
cated on the next page, using a marker.
Chill the new valve guides in a freezer for about an
hour.
Heat the cylinder head to 130°C-140°C (275°F-
290°F) with a hot plate or oven. Do not heat the cyl-
inder head beyond 150°C (300°F). Use temperature
indicator sticks, available from welding supply
stores, to be sure the cylinder head is heated to the
proper temperature.
11-18