The Kawasaki ZRX1200 is a standard
motorcycle or "naked bike" with a liquid-cooled, 1164-cc, in-line four cylinder engine. Built to remind
riders of the simple-but-powerful Universal Japanese Motorcycle (UJM) of the
1970s, the ZRX features Nikasil-plated, aluminum engine cylinders that weigh
less than the cast iron or steel-lined cylinders used in some classic
motorcycles. As a cylinder liner, Nikasil reduces wear and friction - even in
very large cylinder bores with tight tolerances. Over time, however, even
Nikasil-plated engine cylinders need flexible honing to restore
their crosshatched pattern.
Crosshatching and Engine Lubrication
As the motorcycle mechanics at DragBikeZone.com know,
cylinder walls won't retain adequate oil without a crosshatched pattern of properly-angled
grooves. In addition to causing engine problems such as wear and chattering, improper
engine lubrication can prevent piston rings from properly seating during break-in.
That's why an experienced Kawasaki ZRX1200 owner named rgeorge chose the Flex-Hone tool from Brush Research Manufacturing (BRM) for his engine rebuild
project.
After discovering that all four of
his bike's cylinders had "much noticeable wear" but were "still perfectly
round", rgeorge used an flexible engine hone from BRM to restore the
cross-hatch pattern needed for proper oil retention and sealing. The Flex-Hone tool that he
chose was an 83-mm, 240-grit aluminum oxide (AO) engine hone. "These flexible hones are oversized to provide
preload to the cylinder walls," the biker explained, noting that his cylinder
bores are 84-mm.
Cylinder Honing for Plateau Finishing
Built with a coated
metal stem and flexile nylon filaments, the Flex-Hone features abrasive
globules that restore crosshatching and impart a plateau finish. Self-centering and
self-aligning to the bore, the Flex-Hone is not a material removal tool.
Although it will not correct out-of-roundness or remove taper from a cylinder, BRM's
flexible hone is ideal for freshening a cylinder prior to re-ringing.
As a biker named
Y2KZX12R added, "a plateau finish is what modern bike cylinders need to have
with these low tension hard rings". For his part, rgeorge was plenty pleased
with his cylinder measurements. After using the Flex-Hone to restore the surface finish, the mechanic
measured each engine cylinder in six places: top, middle, and bottom; front to
back; and side-to-side at each height. "The cylinders were still perfectly
round," he reported, "front-to-back or side-to-side made no difference".
Author's Note: This CR4 blog entry originally appeared in BRM's Flex-Hone Blog
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