HAIMA 7 - Check of Piston, Piston Ring and Piston Pin

Cylinder block and crank connecting rod mechanisms
77
I/D of cylinder mm{in}
Size Diameter
Standard
84～84.03{3.3071～3.3083}
Oversize: 0.25{0.01}
84.25～84.28{3.3169～3.3181}
Oversize: 0.50{0.02}
84.50～84.53{3.3268 3.3280}
Check of piston, piston ring and piston pin
1. Measure the piston diameter in the direction perpendicular to the axis of the piston
pin hole and 28mm {1.10in} below the lower edge of oil ring groove.
Piston diameter mm {in}
Size Diameter
standard
83.97～84{3.3059～3.3071}
Oversize: 0.25{0.01}
84.22～84.25{3.3157～3.3169}
Oversize: 0.50{0.02}
84.47～84.50{3.3256～3.3268}
2. Calculate the clearance between the piston and cylinder. Replace the piston or
rebore the cylinder when necessary to be applicable to the oversized piston.
Standard clearance: 0.02～0.04mm{0.000～0.0016in}
Max.clearance: 0.10mm {0.004in}
3. If the piston replaced, the replacement of piston ring shall be also done.
4. Measure, with a feeler, the clearance on the entire perimeter between the piston ring
and ring groove (as shown in Fig.) Replace the piston and piston ring when
necessary.
Standard clearance:
1
st
ring: 0.030～0.070mm{0.0012～0.0028in}
2
nd
ring: 0.020～0.060mm{0.0008～0.0024in}
Oil ring: 0.040～0.12mm{0.0016～0.047in}
Max.clearance
1
st
and 2
nd
rings: 0.15mm{0.006in}; Oil ring: 0.15mm {0.006in}