Wednesday, September 7, 2011

Flex-Hones and Motorcycle Engines -Rebuilding a Honda CB550

Two bikes for 300 bucks was a deal too good to resist. Sure, only one of the motorcycles had an engine, but the other was a 1974 Honda CB550. This 544-cc four-cylinder motorbike needed serious work, but sxecafe of Do The Ton set a budget and build a parts list. During the 1950s, British bikers tuned their cafĂ© racers to reach 100 mph, or “the ton” in U.K. slang. Although most modern sports motorcycles can reach triple digits in third gear, Do The Tonners are old-school tuners, but with new-school tools such as flexible hones, honing oil, and cylinder wash brushes.

The Honda CB550
“It’s a great day when it finally happens, the tools arriving I mean”, explained sxecafe while describing his engine rebuild. With its air-cooled, eight-valve, SOHC transverse four, the Honda CB550 motorcycle once delivered 50 bhp at 8,500 rpm, 30.4 lbf at 7,500 rpm, and a blazing 102 mph. These power and speed specifications surely seemed a thing of the past, however, as sxecafe examined each “dirty nasty bore wall” in the 35 year-old motorcycle engine.

Hand Drills, Hones, and Hobbyists
First, he attached his Flex-Hone to a hand drill and then loaded the abrasive “dingle berries” with a high-quality honing oil. These “dingle berries”, as the abrasive globules on flexible hones are known, produce a controlled surface finish that’s free of cut, torn, or folded metal. Flex hones work better when wet, but best of all with a high-quality honing oil. Although hobbyists have used flexible hones when dry, this can result in decreased tool life and the embedding of cast-off material into the workpiece. For best results, always use a blend of oils and wetting agents such as those found in Flex-Hone Oil.

Then see the job through. As a final step, sxecafe used warm water, a mild detergent, and a cylindrical wash brush to clean the cylinder walls. Made with 6-12 nylon for efficient cleaning after honing, these wash brushes are available in standard diameters ranging from 3.5” to 6.5”, but also in special diameters to 14”. By using new-school tools to restore old-school motorcycle engines, hobbyists like sxecafe may one day “do the ton” on their rebuilt rides.

Additional Reading
Doing The Ton
Honda CB550

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