Honda CRF50F 2004-2015 Service Manual page 87

CYLINDER HEADIVALVES
Ream the guides to remove any carbon deposits
before measuring the guide.
Insert the reamer from the combus tion chamber
side of the head and always rotate the reamer clock- ..............
~~"''''!~
wise.
!=
TOOL:
Valve guide reamer, 5.0 mm
07984· MA60001 or
07984-MA6000D
(U .S.A. only)
Measure and record each valve guide 1.0.
SERVICE LIMIT: IN/ EX: 5.03 mm (0.198 in)
Subtract each valve stem 0.0. from the correspond-
ing gu ide 1.0. to obtain the stem-to-guide clearance.
SERVICE LIMITS:
IN: O.OS mm (0.003 in)
EX: 0.10 mm (0.004 in )
Raface lhe
wive
If the st em-la-guide clearance is Qui of specification,
sears whenever rhe
determine if a new guide with standard dimensions
valve
guides are
would bring the clearance within t olerance. If so,
replaced (page
7·12) replace any guides as necessary and ream t o fit
Do not use a torch
to heat the cylinder
head. rt may cause
warping
If the st em·to·gu ide clearance is out of specification
with a new gu ide, also replace the valve.
VALVE GUIDE REPLACEMENT
Chill new valve guides in the freezer section of a
refrigerator for about an hour.
Heat the cylinder head to 212 - 302
O F t100 -150
"e)
with a hot plate or oven.
Support the cylinder head and drive Oul the valve
guides out of the cylinder head from the combus·
tion chamber side.
TOOL:
Valve guide driver, 5.0 mm 07942·MA60000
Coal new O-rings with engine oil and install them
onto new valve guides.
While the cyl i nder is slill healed, drive the new
guides in the cylinder head from the camshaft side
until they are fully seated.
TOOL:
Valve guide driver, 5.0 mm
07942-MA60000
Let the cylinder head cool t o room tempera ture.
VALVE GUIDE DRIVER
VALVE GUIDE DRIVER
7-11