Kubota G2160, Workshop Manual

Page: 94 / 395

1-S34
G2160, WSM ENGINE
Correcting Valve and Valve Seat
NOTE
■
• Before correcting the valve and seat, check the valve stem
and the I.D. of the valve guide section, and repair them if
necessary.
• After correcting the valve seat, be sure to check the valve
recessing.
1) Correcting Valve
1. Correct the valve with a valve refacer.
2) Correcting Valve Seat
1. Slightly correct the seat surface with a 0.79 rad (45
°
) valve seat
cutter (Code No. 07909-33102).
2. Fitting the valve, check the contact position of the valve face and
seat surface with red lead. (Visual check) [If the valve has been
used for a long period, the seat tends to come in contact with the
upper side of the valve face.]
3. Grind the upper surface of the valve seat with a 0.26 rad (15
°
)
valve seat cutter until the valve seat touches to the center of the
valve face (so that a equals b as shown in the figure).
4. Grind the seat with a 0.79 rad (45
°
) valve seat cutter again, and
visually recheck the contact between the valve and seat.
5. Repeat steps 3 and 4 until the correct contact is achieved.
6. Continue lapping until the seated rate becomes more than 70
%
of the total contact area.
W10319540
Valve Lapping
1. Apply compound evenly to the valve lapping surface.
2. Insert the valve into the valve guide. Lap the valve onto its seat
with a valve flapper or screwdriver.
3. After lapping the valve, wash the compound away and apply oil,
then repeat valve lapping with oil.
4. Apply prussian blue to the contact surface to check the seated
rate. If it is less than 70%, repeat valve lapping again.
IMPORTANT
■
• When valve lapping is performed, be sure to check the valve
recessing and adjust the valve clearance after assembling
the valve.
W10309820
Valve face angle Factory spec.
0.79 rad
45.0
°
Valve seat angle Factory spec.
0.79 rad
14.0
°
(a) Identical Dimensions
(b) Valve Seat Width
(c) 0.26 rad (15
°
)
(d) 0.26 rad (15
°
)
(e) 0.79 rad (45
°
)
(A) Check Contact
(B) Correct Seat Width
(C) Check Contact
KiSC issued 11, 2006 A