If you use CPN and CPN2 piston rings, it is recommended plateau honing with a cylinder bore cross hatch angle of 35-40 degrees as show in the diagram. To reach this roughness, the manufacturers of honing machines and accessories recommend using for a gray cast iron engine block and Nikasil cylinders: a) Conventional stones #220 - #280 grit or b) Diamond stones #325 - #550 grit. After honing with either the conventional or diamond stone, the same manufacturers suggest to finish your honing by smoothing the surface with a fine grit conventional abrasive (#400 - #600 grit) or to sweep the bores with a flexible brush or a nylon bristle plateau honing tool. This is necessary to get rid of jagged peaks and folded or torn material. Important Note: Be sure to confirm with your honing equipment manufacturer that the recommended stone grit will produce the following Rz and Ra roughness recommendations. Rz = 59 - 138 μ in [=1.5 3.5 μm] or Ra = 15 - 35 μ in [=0.4 0.9 μm]
