PISTON, PISTON RING, PISTON PIN INSPECTION

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1.  Measure the piston outer diameter using a micrometer.The measurement position is ZJ: 8.7—12.7 mm {0.35—0.50 in}, ZY and Z6: 8.5—12.5 mm{0.34—0.49 in}from the lower end of the piston, and in the thrust direction.

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Piston outer diameter
ZJ: 73.970—74.004 mm {2.9122—2.9135 in}
ZY: 77.970—78.004 mm {3.0697—3.0710 in}
Z6: 77.970—77.980 mm {3.0697—3.0700 in}

2.  Calculate the piston-to-cylinder clearance from the cylinder bore inner diameter and the piston outer diameter.

•  If it exceeds the maximum specification, replace the piston or the cylinder block.
•  The piston clearance may be in error even if the cylinder bore diameter and the piston circumference are correct In this case, take appropriate measures to assure the correct piston clearance.
Standard clearance
-0.004—0.043 mm {-0.0002—0.0169 in}
Maximum clearance
ZJ: 0.065 mm {0.0026 in}
ZY: 0.070 mm {0.0028 in}
Z6: 0.090 mm {0.0035 in}

3.  Measure the piston-to-ring groove clearance around the entire circumference using a feeler gauge.

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•  If it exceeds the maximum specification, replace the piston ring.
Standard clearance
Top: 0.030—0.065 mm {0.0012—0.0025 in}
Second: 0.03—0.07 mm {0.0012—0.0027 in}
Oil: 0.04—0.15 mm {0.0016—0.0059 in}
Maximum clearance
Top, Second: 0.15 mm {0.0059 in}
Oil: 0.20 mm {0.0078 in}

4.  After inserting the piston ring into the cylinder, press in the piston ring to the position 35 mm {1.38 in} from the cylinder surface using the piston.

5.  Measure the piston ring end gap using a feeler gauge.

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•  If if exceeds the maximum specification, replace the piston ring.

Standard end gap

Piston ring

ZJ

ZY, Z6
Top
0.13—0.23 mm {0.006—0.009 in}
0.14—0.24 mm {0.006—0.009 in}
Second
0.23—0.50 mm {0.010—0.019 in}
0.24—0.39 mm {0.010—0.015 in}
Oil (rail)
0.10—0.70 mm {0.004—0.027 in}

Maximum end gap
1.0 mm {0.039 in}

6.  Measure the piston pin hole diameter. Measurement positions total eight and they are in the X and Y directions at four points (A, B, C, and D) as shown in the figure.

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Standard inner diameter
ZJ: 17.988—18.000 mm {0.7082—0.7086 in}
ZY, Z6: 18.988—19.000 mm {0.7476—0.7480 in}

7.  Measure the piston pin outer diameter using a micrometer. Measurement positions total eight and they are in the X and Y directions at the four points (A, B, C, and D) as shown in the figure.

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Standard outer diameter
ZJ: 17.974—17.980 mm {0.7077—0.7078 in}
ZY, Z6: 18.974—18.980 mm {0.7471—0.7472 in}

8.  Calculate the clearance between the piston pin hole diameter and the piston pin outer diameter.

•  If not within the specification, replace the piston or the piston pin.
Standard clearance
0.008—0.026 mm {0.0004—0.0010 in}