Harley-Davidson Big Bore Kits

Ready to take your Milwaukee-Eight engine build further? Explore S&S big bore kits at Kruesi Originals, with displacement upgrade options for compatible factory 107, 114, and 117 cubic-inch engines.

Browse 124, 128, and 129 cubic-inch big bore configurations and verify the correct kit, supporting components, and tuning requirements for your specific Harley-Davidson build.

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  • S&S 107" to 129" Big Bore Kit for M8 Models

    S&S 107" to 129" Big Bore Kit for M8 Models

    S&S 107" to 129" Big Bore Kit for M8 Models

    $1,643.95
    Sale price  $1,643.95 Regular price 
  • S&S 114"/117" to 128" Big Bore Kit for M8 Models

    S&S 114"/117" to 128" Big Bore Kit for M8 Models

    S&S 114"/117" to 128" Big Bore Kit for M8 Models

    $1,561.95
    Sale price  $1,561.95 Regular price 
  • S&S 107" to 124" Big Bore Kit for M8 Models

    S&S 107" to 124" Big Bore Kit for M8 Models

    S&S 107" to 124" Big Bore Kit for M8 Models

    $1,632.95
    Sale price  $1,632.95 Regular price