Honda CRF450R 2009 Service Manual page 267

The valves cannot
be ground. If
8
valve face is burned
or badly worn or
if
it
contacts the sear
unevenly, replace
the
valve.
Follow the refacing
manufacturer"s
operating
ins/ructions.
Inspecllhe valve seal face for:
Uneven seal width:
- Replace the valve and rafaca the valve seat.
Damaged face:
- Replace the valve and reface the valve seat.
Contact area (too high or 100 low)
- Reface the valve seal.
VALVE SEAT REFACING
Valve seat cUllersfgrinders or equivalent valve seat
retacing equipment are recommended to correct worn
valve seats.
If the contact area is too high on the valve, the seat
must be lowered using a 32° nat cutter.
If the contact area is too Iowan the valve. the seat must
be raised using a
60·
interior culler,
CYLINDER HEADNALVES
DAMAGED FACE
UNEVEN SEAT WIDTH
I
TOO LOW
TOO HIGH
I
- " 60"
\
CONTAC~TTOO HIGH ~~~gTSHEAT
I
. . 32"
/
CONTACT TOO LOW OLD SEAT
'T ..
~:DT~o"
9-25