S&S Cycle 631 Camshaft for 1984-1999 Harley-Davidson Big Twins

S&S Cycle 631 Camshaft for 1984-1999 Harley-Davidson Big Twins

The S&S 631 camshaft is built for high-compression Big Twin builds that come alive at higher RPM, delivering an upper-range power surge that rewards aggressive riding. With best performance above 4500 rpm, the 631 is the choice for builders who want a cam that matches a serious engine – one built to push beyond the ordinary.

Key Features

• Upper-RPM-focused power profile for high-compression Big Twin builds
• Best power from 4500 rpm and above
• For all high-compression engines at 11:1 and higher
• Compatible with solid or hydraulic tappets
• Requires high-lift valve springs
• Made in the USA

Technical Specifications

• Lift: .631″
• Engine Compatibility: All Big Twin displacements at 11:1 and above compression
• Power Range: 4500 rpm and up
• Tappet Type: Hydraulic or solid
• Spring Requirement: High-lift springs required

Fitment Notes

• Fits 1984-1999 Harley-Davidson Big Twin models
• For high-compression engines 11:1 and above
• Requires high-lift valve springs
• Installer must verify coil bind, valve-to-valve clearance, valve-to-piston clearance, and cam lobe-to-case clearance
• Review the Fitment tab for complete year and model breakdown