Suzuki DF 2.5 Service Manual page 81

Valve seat contact width
Measure the valve seat contact width as follows.
1. Remove all carbon from the valve and seat.
2. Coat the valve seat evenly with Prussian Blue (or equiva-
lent).
3. Install the valve into the valve guide.
4. Put the valve lapper on the valve head.
 09916-10911: Valve lapper
5. Rotate the valve while gently tapping the valve contact area
against the seat.
6. Continuously pattern on the valve seating face with Prussian
blue.
7. Measure the valve seat contact width A.
 09900-20101: Vernier calipers
Valve seat contact width A:
Standard: IN. & EX. 0.8 – 1.0 mm (0.03 – 0.04 in)
If measurement exceeds specification, repair valve seat.
NOTE:
Clean and assemble the cylinder head and the valve compo-
nents.
Fill the intake and the exhaust ports with solvent in order to
check for leaks between the valve seat and the valve.
If any leaks occur, inspect the valve seat and the face for burrs
or other things that could prevent the valve from sealing.
POWER UNIT 6-15