Kubota M5040 Workshop Manual page 181

M5040, M6040, M7040, WSM
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 spec.
(Intake and exhaust)
2) Correcting Valve Seat
1. Slightly correct the seat surface with a 0.785 rad (45 °) valve seat
cutter.
2. Resurface the seat surface with a 0.262 rad (15 °) valve seat
cutter so that the width is close to specified valve seat width.
Valve seat width
Factory spec.
(Intake and exhaust)
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.
Valve seat angle
Factory spec.
(Intake and exhaust)
(1) Valve Seat Width
(2) Identical Dimensions
Free Length and Tilt of Valve Spring
1. Measure the free length (B) with vernier calipers.
measurement is less than the allowable limit, replace it.
2. Put the spring on a surface plate, place a square on the side of
the spring, and check to see if the entire side is contact with the
square. Rotate the spring and measure the maximum (A). If the
measurement exceeds the allowable limit, replace.
3. Check the entire surface of the spring for scratches. Replace it,
if any.
Tilt (A) Allowable limit
Factory spec.
Free length (B)
Allowable limit
(A) Tilt
1-S55
ENGINE
0.785 rad
45 °
3.3 to 3.6 mm
0.1299 to 0.1417 in.
0.785 rad
45 °
(A) Check Contact
(B) Correct Seat Width
(C) Check Contact
(a) 0.262 rad (15 °)
(b) 0.785 rad (45 °)
(c) 0.523 rad (30 °)
W10283500
1.0 mm
0.039 in.
35.1 to 35.6 mm
1.3819 to 1.4016 in.
34.6 mm
1.3622 in.
(B) Free length
W1063303
KiSC issued 06, 2008 A
If the