Montesa COTA 4RT RACE REPLICA Owner's Manual page 84

Engine servicing
(1) ROUGHNESS
 Contact area (too high or too low)
– Reface the valve seat.
The valves cannot be ground, If a valve face is burned
or badly worn or if it contacts the seat unevenly, replace
the valve.
4-26 4-26
1
32º
Valve Seat Refacing
Valve seat cutters.grinders or equivalent valve seat
refacing equipment are recommended to correct worn
valve seat.
Follow the refacing manufacturer's instructions.
45º
60º
If the contact area is too high on the valve, the seat must
be lowered using a 32˚ flat cutter.
If the contact area is too lower on the valve, the seat
must be raised using a 60˚ interior cutter.
32º
60º