S&S Cycle 129" Power Package Engine Kit for 107" M8

Elevate your riding experience with the S&S Cycle 129" M8 engine kit, a comprehensive power package designed to dramatically increase the performance of your Harley-Davidson Milwaukee-Eight 107" engine. This bolt-on kit transforms your motorcycle's displacement to a formidable 129", delivering a significant boost in horsepower and torque without requiring any case machining.

Description

The S&S Cycle 129" Power Package is engineered for motorcycle enthusiasts seeking a significant upgrade in power and reliability. This high-performance kit features a large 4.320" bore cylinder paired with robust 11.0:1 forged pistons, providing the foundation for an impressive displacement increase from 107" to 129". Installation is straightforward, as it's a true bolt-on solution that retains your stock engine height and works seamlessly with original crankcases, eliminating the need for complex and costly case machining. At the heart of this system is the S&S oil pump/cam plate, meticulously designed with independent scavenge sections for both the flywheel cavity and cam chest, ensuring optimal oil evacuation. Debris screens in both scavenge pickups and a magnet in the cam chest actively prevent contaminants from reaching the oil pump, extending engine life. You'll also benefit from increased oil flow capacity on both the feed and scavenge sides, alongside an adjustable pressure relief valve that can be fine-tuned even after installation. The valvetrain is upgraded with S&S Quickee pushrods and tubes, premium tappets, and billet aluminum hard-anodized black coated tappet cuffs for superior durability. High-performance conical single-wire valve springs are included, compatible with cams up to 0.605" lift, making this kit adaptable for future modifications. The HPT496 cam is specifically designed for big bore applications, perfectly complementing the increased displacement. Completing the package are MLS (multi-layered steel) head gaskets for a reliable seal and a distinctive 129 cam cover badge. Proudly made in the USA, this kit maintains your original engine serial numbers and is compatible with both stock and S&S roller rocker arms, as well as first and second-generation stock valve springs.

Features & Highlights

• Significant Displacement Increase: Transforms your 107" Milwaukee-Eight engine to 129" with a 4.320" big bore cylinder and 11.0:1 forged pistons for a substantial power boost.
• Hassle-Free Bolt-On Installation: Designed as a direct fit, requiring no case machining and retaining stock engine height, making the upgrade process simpler and more cost-effective.
• Optimized Oiling System: Features an S&S oil pump/cam plate with independent scavenge sections, debris screens, a cam chest magnet, and increased flow capacity for superior lubrication and engine protection.
• Premium Valvetrain Components: Includes S&S Quickee pushrods, premium tappets, billet aluminum tappet cuffs, and high-performance conical valve springs (up to 0.605" lift) for enhanced durability and performance.
• Purpose-Built HPT496 Cam: Engineered specifically for big bore applications, ensuring optimal valve timing and power delivery for the increased displacement.
• Comprehensive Compatibility: Works seamlessly with stock crankcases, stock and S&S roller rocker arms, and both generations of stock valve springs, while retaining original engine serial numbers.
• Made in the USA Quality: Manufactured with precision and pride in the United States, guaranteeing high-quality materials and craftsmanship.

Technical Specifications

• Product Name: Power Package
• Type: Engine Performance Kit
• Model: HPT496 Series
• Displacement: 129"
• Bore Size: 4.320"
• Compression Ratio: 11.0:1
• Cam Drive Type: Chain
• Cooling System: Oil Cooled
• Features: Black Pushrod Tubes
• Color/Finish: Black, Non-Highlighted Fins
• Units: Kit
• Vendor Part Number: 310-1394