Cylinder Block Assembly: Service and Repair

1. Oversize pistons should be determined on the basis of the largest bore cylinder. Piston size identification for 0.50 O.S. has an identification mark of 50 and 1.00 O.S. has an identification mark 100.

NOTE: Size mark is stamped on piston top.

2. Measure outside diameter of piston to be used. Measure it in thrust direction as shown.
3. Based on measured piston O.D. calculate boring finish dimension. Boring finish dimension = piston O.D. + (clearance between piston O.D. and cylinder) - 0.02 mm (0.0008 inch) (honing margin).
4. Bore all cylinders to calculated boring finish dimension.

CAUTION: To prevent distortion that may result from temperature rise during honing, bore the cylinders working from No. 2 to No. 4 to No. 1 to No. 3.

5. Hone to final finish dimension (piston O.D. + clearance between piston O.D. and cylinder). Check clearance between piston and cylinder.
6. Clearance between piston and cylinder is 0.02 - 0.04 mm (0.0008 - 0.0016 inch).

NOTE: When boring cylinders, finish all of four cylinders to same oversize. Do not bore only one cylinder to an oversize.