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 Edge chamfering is a surface finishing technique that smoothes the
edges of cylinder ports so that piston rings seat properly. Cylinder
porting, a related technique, is designed to improve flow characteristics
and promote optimum engine performance. For the two-stroke engines used in
scooters, motorcycles, and mopeds, edge chamfering and port work are important
cylinder restoration tasks. Opening the port and aligning the holes are
critical, but so are achieving proper port timing and accurate port shape. If an
engine builder removes too much material with a file and sandpaper, the
cylinder port may be ruined.
Surface
Finishing, Not Material Removal
That's why experienced bike mechanics choose the Flex-Hone from
Brush Research Manufacturing (BRM). The Flex-Hone is a surface finishing tool,
not a material removal tool. By reducing the rough, uneven peaks of a metal
surface's microstructure, this flexible hone removes only the right amount of
material. Unlike other honing tools, the Flex-Hone also produces an unmatched
controlled surface condition. With their soft cutting action, the tool's
abrasive globules have an independent suspension that makes the Flex-Hone
self-centering, self-aligning to the bore, and self-centering for wear.
Brush
Tools and Cylinder Restoration
For the scooter mechanics at 49ccScoot.Com
Forums, a user named 90GTVert offered a valuable lesson in using
brush tools for edge chamfering and cylinder porting. After using metal-bristled
brushes to clean the cylinder head on his favorite motorbike, 90GTVert began
restoring the cylinder itself. Although the "scuffing" was minor, there was still
"a lot of carbon" to be removed. Next, 90GTVert raised the exhaust port opening
by 1 to 1.5mm. Opening this outlet improved the connection to the exhaust pipe,
but also required "smoothing the port a bit".
The
Flex-Hone for Port Chamfering and Plateau Finishing
After chamfering the port edges,
90GTVert prepared to use his "handy dandy 54mm ball hone". Although some users
call BRM's trademarked tool a ball hone, you know you've got the best if it says Flex-Hone. The
BRM brush tool "did a great job of chamfering the ports even smoother," the
scooter enthusiast explained, "and it knocked out the ridge at the top of the
cylinder", he added. "Just 30 seconds with a ball hone does wonders," he advised
the other members of 49ccScoot.Com Forums. As the picture that accompanies this
blog entry shows, the Flex-Hone tool also produces a cross-hatch pattern for a
plateau
finish and optimum lubrication.
Author's Note: This CR4 blog entry originally appeared in BRM's Flex-Hone Blog.
http://www.flexhoneblog.com/2012/10/edge-chamfering-and-cylinder-porting.html
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