Kubota GR1600EU Workshop Manual page 125

GR1600EU, 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.
Free Length and Tilt of Valve Spring
1. Measure the free length (A) of valve spring with vernier calipers.
If the measurement is less than the allowable limit, replace it.
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 (B).
If the measurement exceeds the allowable limit, replace it.
4. Check the entire surface of the valve spring for scratches.
If there is any problem, replace it.
Factory specification
Free length (A)
Allowable limit
Tilt (B) Allowable limit
(A) Free Length
Valve Spring Setting Load
1. Place the valve spring on a tester and compress it to the same
length it is actually compressed the engine.
2. Read the compression load on the gauge.
3. If the measurement is less than the allowable limit, replace it.
Factory specification
Setting load /
Setting length
Allowable limit
1-S39
ENGINE
9Y1210595ENS0060US0
31.3 to 31.8 mm
1.24 to 1.25 in.
28.4 mm
1.12 in.
1.2 mm
0.047 in.
(B) Tilt
9Y1210595ENS0102US0
65 N / 27.0 mm
6.6 kgf / 27.0 mm
15 lbs / 1.06 in.
55 N / 27.0 mm
5.6 kgf / 27.0 mm
12 lbs / 1.06 in.
9Y1210595ENS0062US0
KiSC issued 11, 2013 A