Valve Seat Inspection/Refacing - Honda 2010 CRF250R Service Manual

Use cutting oil on
Ream new valve guides.
the reamer during
Insert the reamer from the combustion chamber side of
this operation. Take
the cylinder head and always rotate the reamer
care nOllo lilt or
clockwise.
lean the reamer in
the guide while
reaming.
TOOLS:
IN : Valve guide reamer,
S.Omm
EX:Valve guide reamer,
4.Smm
07984·MA60001 or
07984·MA60000
(U.S.A. only)
07HMH·ML00101
0'
07HMH·ML0010B
(U.S.A. only)
Clean the cylinder head thoroughly to remove any
metal particles after reaming and reface the valve seats
(page 8-23).
VALVE SEAT INSPECTION/REFACING
CYLINDER HEADNALVES
Clean the intake and exhaust valves thoroughly to , - -- - - - - - - - - - ,
remove carbon depOSits.
Apply a light coating of Prussian Blue to the valve seal.
Tap the valves and seats using a rubber hose or olher
hand-lapping
1001.
Remove the valve and inspect the valve seat face.
The valve seat conlact should be within the specified
width and even all around the circumference.
STANDARD :
IN/EX: 0.90 - 1.10 mm (0.035 - 0.043 in)
SERVICE LIMIT:
IN/EX: 1.7 mm (0.07 in)
NOTE
• When the service limits are exceeded. replace the
intake valve and recheck the valve seat width.
If the seat width is not within specification, reface the
valve seat (page 8-24).
Inspect the valve seat face for:
Uneven seat width:
- Replace the valve and reface the valve seat.
Damaged face :
- Replace the valve and reface the valve seal.
t
t
DAMAGED FACE
;t
SEAT WIDTH
UNEVEN SEAT WIDTH
8-23