124" / 128" Big Bore Kit for M-Eight Engines
124" / 128" Big Bore Kit for M-Eight Engines
Hoban Brothers Motorcycles
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Fitment
Fitment
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2025 FLHTP Electra Glide Police
2025 FXBR Breakout
2024–2025 FLTRXP Road Glide Police
2024 FLI Hydra-Glide Revival
2023–2025 FLTRT Road Glide 3
2023–2025 FXBR Breakout 117
2023 FLHFB Highway King
2022–2025 FXLRS Low Rider S 117
2022–2025 FXLRST Low Rider ST 117
2022–2023 FLHXST Street Glide ST
2022–2023 FLTRXST Road Glide ST
2022–2023 FLTRKSE CVO Road Glide Limited
2022 & 2025 FXBB Street Bob
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2020–2024 FLTRK Road Glide Limited
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2019–2022 FLHT Electra Glide Standard
2019–2020 FXDRS FXDR 114
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2018–2021 FLSB Sport Glide
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2017–2025 FLHRXS Road King Special
2017–2025 FLHTCUTG Tri Glide Ultra
2017–2025 FLHXSE CVO Street Glide
2017–2025 FLTRX Road Glide
2017–2025 FLRT Freewheeler
2017–2025 FLHTPI Electra Glide Police
2017–2025 FLHP Road King Police
2017–2025 FLHX Street Glide
2017–2024 FLHTK Ultra Limited
2017–2023 FLHXS Street Glide Special
2017–2023 FLTRXS Road Glide Special
2017–2022 FLHR Road King
2017–2021 FLHTKSE CVO Limited
2017–2019 FLHTKL Ultra Limited Low
2017–2019 FLHTCU Electra Glide Ultra
2017–2019 FLTRU Road Glide Ultra
Specifications
Specifications
Precision Engineering: Crafted with attention to detail, the M8 128" Big Bore Kit guarantees a perfect fit and optimal performance for your engine.
Superior Materials: Built from top-grade components to ensure durability, reliability, and longevity under even the most demanding riding conditions.
Comprehensive Upgrade: The kit includes all necessary parts, including cylinders, pistons, and gaskets making it a complete solution for your engine upgrade needs.
Enhanced Performance: Experience a significant increase in horsepower and torque, providing you with faster acceleration, improved throttle response, and a more thrilling ride.
Install Notes
Install Notes
Additional Info
Additional Info
Harley-Davidson Milwaukee-Eight 128” Big Bore Kit Unleash the full performance potential of your Harley-Davidson Milwaukee-Eight engine with our premium 128” Big Bore Kit. Designed for riders who demand real horsepower and torque gains, this kit transforms your stock M8 into a hard-pulling performance motor with stronger acceleration, improved throttle response, and increased top-end power. This kit is engineered to convert: M8 107” → 124” M8 114” / 117” → 128” Built with proven performance components, the kit includes CP forged pistons for strength and durability under high load conditions, along with Cometic gaskets to ensure reliable sealing and long-term engine integrity. Whether you're building a performance bagger, hot street cruiser, or dyno-tuned torque monster, this big bore upgrade delivers the displacement and power increase serious riders are looking for.
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