For use with CPN and CPN2 piston rings, it is recommended that you plateau hone with a cylinder bore cross hatch angle of 35-40 degrees.
To reach this roughness, the manufacturers of honing machines and accessories recommend using the following stones for a gray cast iron engine block and Nikasil cylinders.
Conventional stones: #220 – #280 grit; or
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.
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]
Tech Tip courtesy of CP Pistons