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  • Cycle World

    BIG

    by Kevin Cameron May 12, 2017 5 minutes
    Source: The light weight of these glorious giant pistons is one key to repeated runs using 10,000 or more rpm. Try to visualize the compressed mixture, jetting out of the squish zones as a piston approaches TDC.Angelle Sampey on the S&S Cycle Polaris Pro Stock Motorcycle at Gainesville.

    Let’s make an “elephant” V-twin engine by bandsawing two cylinders off a 454 Chevy Big-Block. That’s 113.5 cubes.

    Puny! The S&S Cycle Pro Stock drag-race engine measures 5-1/8-inch bore by 3-7/8-inch stroke. B-I-G. That’s 159.9ci. To paraphrase Crocodile Dundee, “That’s an engine!” Stare in wonder at its gaping injection throttle bodies. This hugeness, remarkably, revs past 10,000 rpm.

    Three engines compete in National Hot Rod Association (NHRA) Pro Stock Motorcycle (PSM): the Vance & Hines “Harley-Davidsons,” the S&S V-twins (once billed as Buells, now as Victorys), and the higher-revving GS-based Suzukis, which get “only” 107 cubes. A quick Pro Stock run in the quarter-mile is 6.750 seconds, reaching 195 to 199 mph through the lights. Engines are unsupercharged, burn gasoline fuel, and produce roughly 350 hp. Bikes in the class are limited to a 70-inch

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