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HOME » 131 Monster Big Bore Kit











Revolution Performance 131" Monster Big Bore Kit

(Fits Twin Cam style motorcycles with 4.625" stroke crankshaft)

$1,189.95

The Revolution Performance 131" Twin Cam Monster Big Bore Kit is the key component to build a devastating 131" Twin Cam engine. The monster 131" kit comes with our state of the art all aluminum NSC plated cylinders which last longer and run cooler than the OEM cylinders. The cylinders are matched with a premium forged piston kit and a Cometic head and base gasket kit.

    131" Monster Big Bore Kit comes with:

  • NEW 4.250" all aluminum Nickel Silicon Carbide (NSC) plated cylinders in your choice of finish: All Black, Black Highlighted, Granite or Natural
  • 11.5:1 compression ratio flat-top piston kit
  • Cometic head and base gasket kit (.030 head gasket / .020 base gasket)
  • The 131" Monster Big Bore Kit requires additional engine modifications to install and benefit from our other products and services.

    Need more than a big bore kit? Click HERE for our complete 131" complete speed shop engine kit.


    Required Services:

  • Case bore service
  • Crank balance service
  • Recommended Services:

  • 131" Monster CNC Cylinder Head Porting Package

    ***NOTE: Compression ratio calculated using 86cc chamber.**

    ***NOTE: Requires S&S 4-5/8" stroker crank, larger throttle body/injectors and fits 2006-2017 Twin Cam models***

    ***NOTE: Dyno chart represents 131" Bolt-On Big Bore Kit, Monster CNC head porting, Feuling .630 cams, 62mm HPI throttle body, D&D Boarzilla exhaust***




For questions on our big bore kits, please contact our sales technicians directly at: 1-866-892-2109 M-F 8:30 A.M. - 5:00 P.M. CST.



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