Kubota WG1605-G-E3 Workshop Manual page 120

WG1605-G-E3,WG1605-L-E3,WG1605-GL-E3, WSM
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.
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.
Factory
Valve face angle specifica-
tion
2) Correcting Valve Seat
1. Slightly correct the seat surface with a 1.0 rad (60 °) valve seat
cutter.
2. Resurface the seat surface with a 0.52 rad (30 °) valve seat
cutter so that the width is close to specified valve seat width
(2.12 mm, 0.0835 in.).
3. After resurfacing the seat, inspect for even valve seating, apply
a thin film of compound between the valve face and valve seat,
and fit them with valve lapping tool.
4. Check the valve seating with prussian blue. The valve seating
surface should show good contact all the way around.
Factory
Valve seat angle specifica-
tion
(1) Valve Seat Width
(2) Identical Dimensions
1-S42
ENGINE
9Y1210318ENS0094US0
1.0 rad
IN.
60 °
1.0 rad
EX.
60 °
1.0 rad
IN.
60 °
1.0 rad
EX.
60 °
(A) Check Contact
(B) Correct Seat Width
(C) Check Contact
(a) 0.52 rad (30 °)
(b) 1.0 rad (60 °)
(c) 0.52 rad (30 °)
9Y1210661ENS0064US0
KiSC issued 01, 2012 A