S&S Cycle 55mm Performance Manifold For Harley M8 2017-2025

S&S 55mm Performance Manifold: Bulletproofing the M8 Intake

The S&S Cycle 55mm Performance Manifold for 2017-2025 Milwaukee-Eight models represents the 2026 pinnacle of intake engineering. For owners of the M8 platform, the factory-equipped plastic intake manifold is a notorious “weak point.” Over time, the intense heat cycles of the cylinder heads cause the plastic flange area to warp and distort, leading to air leaks that result in erratic idling, popping on deceleration, and lean-running conditions. S&S addresses this vulnerability by utilizing a heavy-duty cast aluminum construction. This manifold provides the structural rigidity required to maintain a perfect seal against the intake ports, ensuring that your 2026 tuning remains consistent and your engine remains protected. For the rider seeking secure, industrial-strength utility, the S&S aluminum manifold is a mandatory upgrade for any serious 2026 build.

Optimized Airflow and Increased Volumetric Efficiency

What sets the S&S 55mm manifold apart in the 2026 marketplace is its superior internal flow characteristics. While the factory unit has casting flash and abrupt transitions that can cause air turbulence, the S&S version features CNC-machined surfaces and a refined internal taper. This 55mm bore is specifically sized to match the factory throttle body perfectly while providing a smoother path for the air-fuel charge to enter the 4-valve heads. This results in an immediate improvement in throttle response and a measurable gain in torque across the mid-range—exactly where 2026 touring riders need it most. By increasing the volumetric efficiency of the engine, this manifold allows your Stage 1 or Stage 2 upgrades to breathe at their full potential, providing the high-output 2026 presence that defines a well-built Milwaukee-Eight.

Expert Installation & Performance Advice

As specialists in Milwaukee-Eight engine architecture, we recommend this manifold as the first step for any 2026 engine build. Pro Tip: When installing, always use a small amount of non-corrosive lubricant on the O-rings to ensure they seat properly without pinching. Installation Note: To verify if your current plastic manifold is leaking, spray a small amount of brake cleaner near the intake flanges while the bike is idling; if the RPM changes, you have a leak. Maintenance Note: Ensure the manifold support bracket is properly torqued to prevent vibration-induced stress on the intake flanges during 2026 tours. Safety Note: Because this manifold improves airflow, we highly recommend verifying your AFR (Air-Fuel Ratio) with a Dynojet Power Vision or Fuelpak FP4 to ensure optimal cooling and performance throughout the 2026 riding season.

The Professional Standard for M8 Intake Reliability

Choosing the S&S Cycle 55mm Performance Manifold means investing in unmatched mechanical stability and a refined intake signature. It offers a unique combination of modern metallurgical strength and a flow-tested design that honors the performance legacy of the Harley-Davidson brand. For the rider who wants a high-output 2026 presence and a flawless engineering finish, the S&S 55mm Manifold is the unmatched leader. Seal the leak, boost the flow, and ride the distance.

Features:

• High-Flow, adds 3–5 hp
• Must have for big bore engines
• CNC Machined
• T6 heat treated cast aluminum
• Replaces stock, plastic manifold
• Includes new rubber seal
• Easy to Install
• Exempt from emissions tampering regulations under CARB EO# D-355-39

Product Style	AmericanV-twin Item #	Catalog Number	Store Sku	MFR. Product #	Availability
S&S Cycle 55mm Performance Manifold For Harley M8 2017-2025	98734	98734	23535	160-0241A	In Stock: Ships within 24 hours