Fourth of July boating means more than just fuel, food, fireworks,
and fun. For boat owners across the
United States (and around the world), engine performance can be the difference
between a relaxing day on the water and a frustrating day at the marina. As Bob Gritz of iboats.com
learned, damaged pistons can cause a marine engine to misfire, loose power, and
idly poorly. Without enough crankcase
pressure, a cylinder cannot push enough fuel through the ports to the
combustion chamber.
Cylinder Honing for Boat
Engines
In Bob Gritz's two-stroke 15-hp Johnson engine, "a rogue
piece of carbon" passed through the crankcase and into the top cylinder, where
overheating (probably from over-revving) caused the piston to expand. Although
the piston skirt became glazed and blued, the cylinder walls were hardened and thus
avoided serious scoring. "The cylinder walls looked pretty good," Bob noted,
but also added that "they should be honed and then measured". The tool he chose
wasn't a rigid honing stone, but a flexible hone from
Brush Research Manufacturing (BRM).
Flexible Honing and
Surface Finishing
Made with a stiff metal stem and flexible nylon filaments,
BRM's Flex-Hone tool features abrasive globules that are ideal for surface finishing
cylinder walls. By polishing the metal gently, the Flex-Hone "freshens"
cylinders prior to re-ringing, but is not a material-removal tool. Available in numerous sizes,
grits, and abrasive types, the Flex-Hone is used for engine block honing,
surface finishing, deburring, and cylinder deglazing. Self-centering and self-aligning
to the bore, the tool mounts in an electric hand drill and is easy-to-use.
More Marine Applications for Flexible Honing
By restoring the crosshatch pattern on a cylinder's walls and
imparting a plateau
finish, the Flex-Hone also ensures optimum lubrication. For boat owners
such as the members of iboats.com, smaller-bore tools are used. Marine service shops use larger-bore flexible hones to maintain the big-bore diesel engines
that power tankers, freighters, and other large ocean-going vessels. In
addition to ship engines, the Flex-Hone is used to refurbish marine pumps and
valves. This versatile, flexible honing tool can be used on marine hydraulic
cylinders, too.
Author's Note: This CR4 blog entry originally appeared in BRM's Flex-Hone Blog.
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