S&S CYCLE Cylinder Head Kit - Big Twin 90-1504

S&S Cycle cylinder heads are engineered to unlock significant performance gains on Big Twin Harley-Davidson engines through improved airflow, combustion efficiency, and valve lift capabilities. Whether you're building a street performance engine or maximizing power output on an existing platform, these fully assembled heads provide the foundation for reliable, repeatable horsepower without compromise. Pairing them with compatible upgrades allows you to dial in exactly the performance level your build demands.

Key Technical Specifications:

• Fully assembled unit
• Stainless steel valves
• High-lift springs (0.640" lift)
• CNC-ported design
• Bolt-on installation
• Reuses stock headbolts
• Compatible with S&S Super Stock pistons
• Made in U.S.A.
• Requires separate intake manifold
• Requires separate piston kit
• Gasket kit sold separately
• Does not include rocker box gaskets
• Big Twin fitment only