Yanmar 3YM30 Sevice Manual page 220

(4) Piston and ring
1) Piston
Inspection item
Piston outside diameter
(Measure in the direction vertical to
the piston pin.)
Piston diameter measure position
(Upward from the bottom end of the piston)
Clearance
between piston and cylinder
Piston pin hole inside diameter
Piston pin outside diameter
Clearance
2) Piston ring
3YM30
Inspection item
Top ring Groove width
Ring width
Side clearance
Ring gap
Second ring Groove width
Ring width
Side clearance
Ring gap
Oil ring Groove width
Ring width
Side clearance
Ring gap
Standard
3YM30 75.965-75.975
3YM20 69.970-69.980
22
3YM30 0.035-0.055
3YM20 0.030-0.050
22.000-22.009
21.995-22.000
0.000-0.014
Standard
1.550-1.570
1.470-1.490
0.060-0.100
0.15-0.30
1.580-1.595
1.430-1.450
0.013-0.165
0.18-0.33
3.010-3.025
2.970-2.990
0.020-0.055
0.20-0.45
205
13. Service standards
Reference
Limit
75.920
69.925
5.3.1(1)
-
-
-
22.039
21.965
0.074
Reference
Limit
page
-
1.450
-
0.390
1.695
1.410
5.3.3(1)
0.285
0.420
3.125
2.950
0.175
0.540
mm
page
5.3.2
mm