S&S Cycle 93 Inch KN93 Knucklehead Engine for Harley-Davidson Big Twin 1936-1999

S&S Cycle 93 Inch KN93 Knucklehead Engine for Harley-Davidson Big Twin 1936-1999

The S&S Cycle KN93 combines the legendary aesthetic of the 1940s Knucklehead with modern engineering for a high-performance, reliable powerplant. This standard compression 93-inch engine delivers significantly more power than stock vintage engines while maintaining a period-correct appearance through the use of Flathead Power (FHP) rocker boxes and vintage-style rocker arm cover tins.

Designed for versatile builds, this engine is available in two distinct crankcase configurations. The Generator Style is for those seeking an authentic vintage fitment in early frames, while the Alternator/Generator Style is engineered for builders using 1970-up primary covers and modern charging systems. Whether you are restoring a 1940s classic or building a high-performance custom, the KN93 provides the “Knuckle” soul with modern-day reliability.

Technical Specifications

• Displacement: 93 Cubic Inch
• Bore: 3-5/8 Inch
• Stroke: 4-1/2 Inch
• Compression Ratio: 8.2:1
• Cylinder/Head Finish: Black Powder Coated
• Crankcase Finish: Natural Aluminum
• Carburetor: S&S Super E
• Ignition: S&S Super Stock Single Fire System
• Valvetrain: S&S solid lifters and polished billet timer

Key Features

• Flathead Power Heritage: Features authentic FHP rocker boxes for a classic profile.
• Modern Flywheel Design: Utilizes 1958-1965 style flywheel assemblies with splined sprocket shafts for superior strength.
• Improved Oil Circuit: Cast-in oil return lines reduce the need for external plumbing and potential leak points.
• Ready to Run: Comes completely assembled from S&S Cycle and includes an oil filter mount.
• Output Performance: Delivers 61.6 Horsepower and 83.7 lb-ft of torque.
• Warranty: Backed by a one-year manufacturer warranty.

Installation and Fitment Notes

Generator Case Fitment: These cases use stock 1936-1947 style motor mounts and will fit stock Knucklehead frames. They can also be used in 1948-1999 frames with the included front motor mount spacer (#31-2017).

Alternator/Generator Case Fitment: These cases use 1948-1999 style front motor mounts and will NOT fit stock Knucklehead frames. They require a 1970-up length transmission main shaft.

Primary Requirements: Both styles utilize a 1958-1965 style flywheel assembly, which requires the use of a 1955-1964 style inner tin primary cover and primary chain sprocket. Custom exhaust fabrication is required.