um DSR EX 125 Workshop Manual page 53

INSPECTION AND REPAIR
Steps for seating valves:
- Apply a coarse abrasive paste to the valve face.
ATTENTION
DO NOT ALLOW THE PASTE TO PENETRATE IN THE SPACE
BETWEEN THE VALVE STEM AND THE VALVE GUIDE.
- Apply acid with molybdenum disulphate to the valve stem.
- Fit the valve into the cylinder head.
-Twist the valve until its face and its seat are uniformly
ground, then remove the paste immediately.
N.B.:
TO OBTAIN THE BEST VALVE SEATING RESULTS, SHAKE
SOFTLY IN THE VALVE SEAT WHILE TWISTING BACKWARDS
AND FORWARDS BY HAND.
- Apply a coarse abrasive paste to the valve face and repeat
the above steps.
N.B.:
MAKE SURE THAT ALL TRACES OF GRINDING PASTE ARE
REMOVED FROM THE FACE OF THE VALVE SEAT AFTER
EVERY VALVE SEATING OPERATION.
- Apply blue mechanical dye (Dykem) to the valve face (b) .
- Fit the valve into the cylinder head.
- Press the valve through the valve guide and against its seat
to obtain a good contact.
- Measure the width of the valve seating (c) once again. If it is
outside that specified, rectify and grind the valve seat.
51 WORKSHOP MANUAL