Make sure all threads are in proper conditions.
Check cylinder sliding surface for signs of friction and scratches. Also check the seal surfaces for damages.
Caution! If the grooves on the cylinder liner are evident, replace the cylinder and the piston.
Clean off lime scales on the cylinder cooling slots.
Measure the cylinder bore at a distance of 10 - 43 - 90 mm (0.39 - 1.69 - 3.54 in) from the head coupling surface; the highest value should be considered to estimate wear limits.
Cylinder bore "C": 92.000 mm (3.6220 - in) C= D1 or D2 max
Cylindricity tolerance: 0.020 mm (0.00079 in)
Replace the cylinder, the piston and the piston ring all together if not complying with specifications.