Kubota GR1600EU Workshop Manual page 124

GR1600EU, WSM
Valve Seating
1. Coat the valve face lightly with prussian blue and put the valve
on its seat to check the contact.
2. If the valve does not seat all the way around the valve seat or
the valve contact is less than 70 %, correct the valve seating as
follows.
3. If the valve contact does not comply with the reference value,
replace the valve or correct the contact of valve seating.
Valve seat width Factory specification
(1) Correct
(2) Incorrect
Correcting Valve and Valve Seat
NOTE
• Before correcting the valve and seat, check the valve stem
and the I.D. of 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.
Valve face angle Factory specification
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 prussian blue. (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 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.
Valve seat angle Factory specification
(1) Valve Seat Cutter
(A) Check Contact
(B) Correct Seat Width
(C) Check Seat Surface
(D) Check Contact
1-S38
ENGINE
2.12 mm
0.0835 in.
(3) Incorrect
9Y1210595ENS0058US0
0.79 rad
45 °
0.79 rad
45 °
(a) Identical Dimensions
(b) Valve Seat Width
(c) 0.26 rad (15 °)
(d) 0.79 rad (45 °)
9Y1210595ENS0059US0
KiSC issued 11, 2013 A