Kubota M6800S Workshop Manual page 113

M6800 · M6800S · M8200 · M9000, WSM
Replacing Valve Guide
(When removing)
1. Using a valve guide replacing tool, press out the used valve
guide.
(When installing)
1. Clean a new valve guide, and apply engine oil to it.
2. Using a valve guide replacing tool, press in a new valve guide
until it is flush with the cylinder head as shown in the figure.
3. Ream precisely the I.D. of the valve guide to the specified
dimension.
IMPORTANT
• Do not hit the valve guide with a hammer, etc. during
replacement.
(A) When Removing
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.
2) Correcting Valve Seat
1. Slightly correct the seat surface with a 1.047 rad (60 °) (intake
valve) or 0.785 rad (45 °) (exhaust valve) seat cutter (Code No.
07909-33102).
2. Resurface the seat surface with a 0.523 rad (30 °) valve seat
cutter to intake valve seat and with a 0.262 rad (15 °) valve seat
cutter to exhaust valve seat 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.
(a) Identical Dimensions
(b) Valve Seat Width
(c) 0.523 rad (30 °) or 0.262 rad (15 °)
(d) 0.262 rad (15 °) or 0.523 rad (30 °)
(e) 0.785 rad (45 °) or 1.047 rad (60 °)
1-S28
ENGINE
(B) When Installing
W1062212
(A) Check Correct
(B) Correct Seat Width
(C) Check Contact
W1028350
KiSC issued 03, 2008 A