What should be the final treatment for a bored cylinder?

When a cylinder is bored, it typically means that it has been enlarged to accommodate new piston components or to remove wear and scoring. After the boring process, honing is the recommended final treatment. Honing is crucial because it enhances the surface finish of the cylinder walls, which helps achieve the correct tolerances needed for piston rings to seat properly.

Honing creates a crosshatch pattern on the cylinder walls, which provides better oil retention and improves the sealing between the piston rings and the cylinder. This is essential for optimal compression and engine performance. Additionally, honing can remove any microscopic irregularities left from the boring process, ensuring that the cylinder is properly prepared for operation.

The other options, while they may seem plausible, do not achieve the desired result as effectively as honing does. For instance, simply leaving the bored cylinder without further treatment would not ensure the right finish for effective sealing. Polishing the cylinder could make it too smooth, which might hinder the oil retention capabilities needed for proper lubrication. Installing new fittings is unnecessary if the cylinder is treated correctly, as the focus should be on the surface finish of the cylinder itself. Therefore, honing is the most suitable method to finalize the treatment of a bored cylinder for optimal engine performance.