The Flex-Hone® for Engine Rebuilds: Cylinder Reconditioning

Cylinder bores are machined into engine blocks to guide pistons, seal combustion chambers, and aid in engine cooling. In aluminum engines, bores may be chrome-plated or fitted with cast iron sleeves or liners to prevent excessive wear. Over time, however, repeated contact between the piston rings and cylinder walls may cause scoring, glazing, or the development of cylinder ridges.

To restore used engines to peak performance, engine remanufacturers and rebuilders must determine whether cylinders bores can be reconditioned. If the bores can be reused, the Flex-Hone® tool from Brush Research Manufacturing (BRM) provides a quick, efficient, and easy-to-use way to recondition the bores in both large and small engines.

Inspecting and Measuring Cylinder Bores
In “Evaluating the Cylinder,” an analysis of cylinder reconditioning methods, the Small Engine Information website explains how to inspect and measure cylinder bores. If a visual inspection reveals that a cylinder wall has score marks, measure the size of the bore and also the roundness and taper. Then compare these measurements to specifications in your engine service manual for maximum wear limit, maximum out of round, and maximum taper allowed.

Honing Engine Cylinders
If cylinder wall scoring is non-existent or shallow, and all bore measurements are within tolerance, your engine cylinder does not need to be machined to a larger size and fitted with oversized pistons. Before reassembling your engine, however, cylinder reconditioning is recommended. For best results, use the Flex-Hone® tool to hone the cylinder walls. Built with a stiff, coated stem and finger-like formations of abrasive globules, this flexible engine hone follows the geometry of the bore to create a uniform surface finish that promotes optimum lubrication.

The Flex-Hone® vs. Rigid Hones
The Flex-Hone® tool from Brush Research produces a controlled surface condition and creates a cross-hatched pattern that’s extremely efficient at creating grooves for oil retention. By contrast, rigid hones or honing stones create unidirectional or uneven grooves that may interfere with optimum lubrication. Available in a variety of sizes, the Flex-Hone® is used with large diesel engines, small two-stroke engines, and by automotive manufacturers and hobbyists alike.

Have you used the Flex-Hone® to recondition engine cylinders? If so, please let us know by commenting on this blog entry.