Lapping Valve; Checking Free Length And Tilt Of Valve Spring; Checking Valve Spring Setting Load - Kubota WSM BX1880 Workshop Manual

3. ENGINE

6.1.10 Lapping valve

IMPORTANT
• When valve lapping is performed, be sure to
check the valve recessing and adjust the valve
clearance after assembling the valve.
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.
6.1.11 Checking free length and tilt of valve
spring
(A) Tilt
1. Measure the free length (B) of valve spring with
vernier calipers. If the measurement is less than the
allowable limit, replace it.
3-60
(B) Free length
BX1880,BX2380,BX2680,RCK60B-23BX,RCK54-23BX,RCK48-18BX,RCK60D-26BX,RCK54D-26BX
BX1880 and BX2380
Factory specifi-
cation
Free length (B)
Allowable limit
BX2680
Factory specifi-
cation
Free length (B)
Allowable limit
2. Put the valve spring on a surface plate, place a
square on the side of the valve spring.
3. Check to see if the entire side is in contact with the
square. Rotate the valve spring and measure the
maximum tilt (A). If the measurement exceeds the
allowable limit, replace it.
BX1880 and BX2380
Tilt (A) Allowable limit
BX2680
Tilt (A) Allowable limit
4. Check the entire surface of the valve spring for
scratches. If there is any problem, replace it.

6.1.12 Checking valve spring setting load

1. Place the valve spring on a tester and compress it
to the same length it is actually compressed in the
engine.
2. Read the compression load on the gauge.
SERVICING
6. Servicing
31.3 to 31.8 mm
1.24 to 1.25 in.
28.4 mm
1.12 in.
37.0 to 37.5 mm
1.46 to 1.47 in.
36.5 mm
1.44 in.
1.2 mm
0.047 in.
1.0 mm
0.039 in.
KiSC issued 03, 2019 A