BOMBARDIER Johnson 90 Service Manual page 190

POWER UNIT
CYLINDER HEAD ASSEMBLY
Valve seat contact width
Measure valve seat contact width as follows:
1 . Remove all carbon from valve and seat.
2. Coat valve seat evenly with Prussian blue (or equivalent).
3. lnstall valve into valve guide.
4. Put valve lapper on valve.
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Valve lapper
5. Rotate valve while gently tapping valve contact area
against seat.
6. Continuously pattern on valve seating face with Prussian
blue.
7. Measure valve seat contact width
®·
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Vernier calipers
Valve seat contact width
®:
Standard:
IN 1.1 -1.3
mm
(0.04-0.05 in)
EX 1.1 -1.3
mm
(0.04-0.05 in)
lf measurement exceeds specification, repair valve seat.
NOTE:
For va/ve seat repair, see "VALVE SEAT SERVICING" sec­
tion on page 6-37.
6-36