BRP Johnson J30TEL4SUA 2007 Service Manual page 148

POWERHEAD
CYLINDER HEAD
Valve Seat Refacing
WARNING
To avoid personal injury, wear eye protec-
tion when using a cutter.
Remove all carbon deposits from the valve and
the valve seat.
Use a 45° angle cutter to reface valve seat.
IMPORTANT:
Turn the cutter in a clockwise
direction, NEVER counterclockwise.
Check the valve seat contact width.
•
If the width is greater than the specification,
reface the valve seat using a 15° angle cutter.
•
If the width is less than the specification, reface
the valve seat using a 45° angle cutter again.
Clean up any burrs by using a 45° angle cutter
very lightly.
1
15°
1. Valve seat
146
45°
001500
Lap the valve on the valve seat in two steps: first
with coarse grit lapping compound applied to the
face, and then with fine grit lapping compound.
Valve Spring
Check the strength of the valve spring by measur-
ing its free length with vernier calipers.
If the spring's free length is less than the service
limit, replace the valve spring.
Valve Spring Free Length
Standard
Service Limit
Use a spring tester to measure the valve spring
preload.
001502
1.865 in. (47.38 mm)
1.791 in. (45.48 mm)
001508