Kubota G21LD / G21HD Workshop Manual page 105

G21LD · G21HD, WSM
Valve Recessing
1. Clean the cylinder head surface, valve face and valve seat.
2. Insert the valve into the valve guide.
3. Measure the valve recessing with a depth gauge.
4. If the measurement exceeds the allowable limit, replace the
valve.
5. If it still exceeds the allowable limit after replacing the valve,
correct the valve seat face of the cylinder head with a valve seat
cutter (Code No. 07909-33102) or valve seat grinder.
6. Then, correct the cylinder head surface with a surface grinder, or
replace the cylinder head.
Factory spec.
Valve recessing
Allowable limit
(1) Cylinder Head Surface
Clearance between Valve Stem and Valve Guide
1. Remove carbon from the valve guide section.
2. Measure the valve stem O.D. with an outside micrometer.
3. Measure the valve guide I.D. with a small hole gauge, and
calculate the clearance.
4. If the clearance exceeds the allowable limit, replace the valves.
If it still exceeds the allowable limit, replace the valve guide.
Factory spec.
Clearance between
valve stem and valve
guide
Allowable limit
Valve stem O.D. Factory spec.
Valve guide I.D. Factory spec.
1-S33
ENGINE
0.10 (protrusion) to
0.10 (recessing) mm
0.0039 (protrusion) to
0.0039 (recessing) in.
0.30 (recessing) mm
0.0118 (recessing) in.
(A) Recessing
(B) Protrusion
W10305870
0.030 to 0.057 mm
0.00118 to 0.00224 in.
0.10 mm
0.0039 in.
5.968 to 5.980 mm
0.23496 to 0.23543 in.
6.010 to 6.025 mm
0.23661 to 0.23720 in.
W10311740
KiSC issued 08, 2007 A