Which statement best describes the correct cylinder boring and honing procedure for an engine rebuild?

Which statement best describes the correct cylinder boring and honing procedure for an engine rebuild?

• A. Bore to new piston size plus clearance
• B. Bore to new piston skirt diameter
• C. Hone to new piston size and bore to clearance specifications
• D. Bore to specified size and hone to the clearance specification

Answer: (D)

The key idea is to set the cylinder bore to the precise finished size required for the piston you’re using, and then finish it with honing to reach the exact piston-to-wall clearance specified by the piston and ring manufacturer. Boring creates the basic cylindrical size and true, round shape, while honing adds the final small-scale surface texture and final diameter to meet tolerance. This sequence ensures the rings can seat properly and seal, while allowing for proper oil control and combustion chamber performance. Boring to the piston skirt diameter or to the piston size plus clearance would not give the correct finished diameter or the correct clearance range, and honing to a piston size rather than to the required clearance wouldn’t produce the proper wall-to-piston gap. The right approach is to bore to the specified bore size first and then hone to the clearance specification.

The key idea is to set the cylinder bore to the precise finished size required for the piston you’re using, and then finish it with honing to reach the exact piston-to-wall clearance specified by the piston and ring manufacturer. Boring creates the basic cylindrical size and true, round shape, while honing adds the final small-scale surface texture and final diameter to meet tolerance. This sequence ensures the rings can seat properly and seal, while allowing for proper oil control and combustion chamber performance.

Boring to the piston skirt diameter or to the piston size plus clearance would not give the correct finished diameter or the correct clearance range, and honing to a piston size rather than to the required clearance wouldn’t produce the proper wall-to-piston gap. The right approach is to bore to the specified bore size first and then hone to the clearance specification.