Description
The S&S Cycle Power Pack delivers the displacement and breathing capacity serious M8 builders need without case machining or extensive fabrication. This bolt-on kit pairs a 4.250″ bore with precision-engineered internals—forged pistons, billet oil pump, premium tappets, and a purpose-built 550 cam—to unlock measurable horsepower and torque gains while maintaining engine reliability. Whether you’re chasing street performance or track-ready power, this kit gives you the engineering and component quality that separates S&S from bolt-together alternatives.
- Bore: 4.250″
- Compression ratio: 11.1:1
- Pistons: Forged
- Installation: Bolt-on
- Case machining: None required
- Oil pump: Billet aluminum
- Oil pump design: Independent scavenge sections
- Scavenge pickups: Dual debris screens
- Cam chest: Magnetic debris trap
- Oil system: Increased flow capacity
- Pressure relief: Adjustable in-engine
- Pushrods: Quickee design
- Tappets: S&S premium
- Tappet cuffs: Billet aluminum
- Tappet cuff benefit: Eliminates distortion
- High-RPM stability: Improved
- Cam: S&S 550
- Cam application: Big bore optimized
- MPN: 310-1105B
