Nikasil is an extremely hard material that’s used to line the surfaces of engine components. Developed by MAHLE in 1967, the electrodeposited nickel-matrix silicon-carbide coating reduces friction and wear, especially in aluminum engines. Although Nikasil is lighter, thinner, and harder than cast iron, some engine builders avoid this high-performance plating material. Because Nikasil coatings are very thin, rigid hones can remove too much of the lining. But that doesn’t mean you can’t deglaze a Nikasil bore, as some mechanics incorrectly claim in on-line discussions.
Deglazing Nikasil Cylinders
At DragBikeZone.com, an “expert class” user debunked this honing myth while rebuilding the engine for a Kawasaki ZRX 1200 motorcycle. After hearing some loud knocking noises, rgeorge tore down his bike’s engine and discovered that “all the cylinders had much noticeable wear”. Although the Nikasil plated bores were “perfectly round with no taper,” the crosshatching was “completely gone” – a problem that prevented engine oil from adhering to cylinder walls. To deglaze the engine cylinders and restore the crosshatch pattern for optimum lubrication, rgeorge choose the Flex-Hone® tool from Brush Research Manufacturing (BRM).
Honing Nikasil Cylinders
Unlike traditional honing tools such as honing stones, the Flex-Hone® is designed for surface finishing – not material removal. Self-centering and self-aligning to the bore, the Flex-Hone® brush tool produces an unmatched controlled surface condition. Available in a variety of abrasive types and grits, BRM’s flexible hone creates an oil-holding cross hatch pattern and a plateau finish that’s free of cut, torn and folded metal. For Nikasil cylinders, BRM recommends a slightly-oversized aluminum oxide Flex-Hone® like the one rgeorge selected. The recommended abrasive type for nikasil plated cylinders is 240 grit aluminum oxide. However, BRM also recommends that you thoroughly inspect the cylinder walls to be sure the nikasil plating is free from any cracking or flaking. If any imperfections are found the cylinder must be replated.
Engine Hones and Abrasive Types
Although other members of DragBikeZone.com argued that rgeorge should have used a diamond hone instead, we’re confident the Kawasaki mechanic made the right choice. Nikasil-coated bores are easier to over-hone than cast iron engine cylinders, for which silicon carbide (SC) is the right choice. Remember that with Nikasil cylinders, aluminum oxide is the right abrasive for cylinder wall deglazing.
Leave A Comment