S&S Cycle 129" Power Package Big Bore Kit for M8

Elevate your Harley-Davidson Milwaukee-Eight engine's performance to an exhilarating new level with the S&S Cycle M8 129" Big Bore Kit. This comprehensive bolt-on power package is engineered to transform your 107" M8 into a formidable 129" powerhouse, delivering significant gains in horsepower and torque without requiring any complex case machining.

Description

Designed for motorcycle enthusiasts seeking a substantial power upgrade, the S&S Cycle M8 129" Big Bore Kit offers a robust solution for your 107" Milwaukee-Eight engine. This high-performance engine kit boosts your displacement to 129" through precision-engineered 4.32" bore cylinders paired with durable 11.0:1 compression ratio forged pistons. The result is a dramatic increase in throttle response and acceleration, providing a more thrilling riding experience. Installation is simplified as this is a true bolt-on kit, eliminating the need for costly and time-consuming case machining. The kit includes an advanced S&S oil pump and cam plate, featuring a striking blue anodized finish. This system incorporates independent scavenge sections for both the flywheel cavity and cam chest, along with debris screens and a magnet in the cam chest, ensuring optimal oil circulation and protection against contaminants. With increased oil flow capacity on both feed and scavenge sides, and an adjustable pressure relief valve, your engine's lubrication is meticulously managed. Further enhancing performance are the Quickee pushrods, premium S&S tappets with billet aluminum, hard-anodized black coated tappet cuffs, and S&S 550 cams specifically designed for big bore applications. Complementing these are S&S valve springs, built to handle cam lifts up to 0.605", featuring a high-performance conical single wire spring design. All necessary gaskets, bearings, and hardware are included for a seamless installation, allowing you to quickly get back on the road and experience the full potential of your M8 engine, proudly Made in the USA.

Features & Highlights

• Massive Displacement Increase: Transforms your 107" Milwaukee-Eight engine into a powerful 129" unit with 4.32" bore cylinders and 11.0:1 compression forged pistons, delivering significant horsepower and torque gains.
• Effortless Bolt-On Installation: Engineered as a true bolt-on kit, eliminating the need for complicated and expensive case machining, making your upgrade process straightforward and efficient.
• Optimized Oil System: Features an S&S oil pump/cam plate with independent scavenge sections, debris screens, and a cam chest magnet, ensuring superior lubrication, filtration, and engine longevity.
• Enhanced Valvetrain Components: Includes S&S 550 cams, Quickee pushrods, premium tappets with billet aluminum cuffs, and high-performance valve springs (up to 0.605" lift) for reliable, high-RPM operation.
• Complete Kit for Convenience: Comes with all necessary gaskets, bearings, and hardware, providing a comprehensive package for a complete and hassle-free installation right out of the box.
• Proudly Made in the USA: Guarantees superior quality, precision engineering, and robust durability, reflecting S&S Cycle's commitment to American craftsmanship.

Technical Specifications

• Brand: S&S Cycle
• Product Type: Performance Kit / Big Bore Kit
• Target Displacement: 129"
• Bore Size: 4.32"
• Stroke Length: 4-3/8"
• Compression Ratio: 11.0:1
• Cooling System: Oil Cooled
• Cam Drive Type: Chain
• Valve Spring Lift Capacity: Up to 0.605"
• Pushrod Tubes: Black
• Cylinder Finish: Highlighted Fins, Wrinkle Black
• Oil Pump/Cam Plate Finish: Blue Anodized
• Tappet Cuffs Material: Billet Aluminum, Hard-Anodized Black Coated
• Country of Origin: USA
• S&S Vendor Part Number: 310-1225C

Important to Know

• Fitment Restriction: This power package is not compatible with any Harley-Davidson Trike models.