Kubota Z400-B Handbuch Seite 171

Valve Seat Width
1. Check the valve seat surface and the width.
2. If the seat width is not within the specified values or (b)
is not equal to (c) (See Figurel, correct the valve seat
referring to "Correcting Valve and Seat".
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5
Correcting Valve and Seat
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.
1. Correct the valve using a valve refacer.
2. Correct the valve seat surface using a valve seat cutter
(Code No.: 07909·33102), following the steps below.
3. Cut the valve seat surface with a 0.75 rad. (45
0
)
valve seat
cutter.
4. Check the seating surface on the valve face using a red
lead.
5. Cut the valve seat surface with a 0.29 rad. (15°) valve seat
cutter so that the width A becomes equal to B (See figure).
6. Check the seating surface using a red lead. If needed,
repeat the steps above from 3, until the valve contacts
correctly.
7. Lap the valve onto its seat using lapping compound, until
the valve contacts with its seat evenly .
• NOTE:
• Before correcting the valve and seat, check the valve stem
and the valve guide, and repair them if necessary.
Valve seat angle!
Factory specification
Valve face angle
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Valve Recessing
1. Clean the valve face and install it in its guide.
2. Measure the valve recessing with a depth gauge.
3. If the recessing exceeds the allowable limit, replace the
valve, cylinder head or both.
0.75
to
0.95
mm
0.0295
to
0.0374
in.
Valve recessing
1.2
mm
0.047 in.
S·89