KNUCKLEHEAD HARLEY ENGINE
kucklehead harley replacement engine

Generator Style

The KN-Series engines are very close in appearance to a stock knucklehead engine, but offer a number of modern features for more power, better engine life, and improved reliability. Aside from the much larger 93 inch displacement, the main improvement in design is the 1958-1965 style flywheel assembly, which uses a splined sprocket shaft and Timken® sprocket shaft bearing. Although this necessitates the use of a 1955-1964 style inner tin primary cover and primary chain sprocket, the increased flywheel stability, strength, and power handling capacity are worth a slight departure from stock.

Rocker arm cover tins are another modern improvement. The lower covers are actually made of die-cast aluminum, and instead of being held in place by the valve guide, they are held down by valve spring pressure. A special gasket and o-ring seal on the bottom of the lower tin provides a positive seal, and is much easier to service if needed, since the valve guides do not have to be pressed out in order to remove the lower covers.

Instead of the steel brazed-in hard oil return lines used on stock tins, S&S has improved the design of the oil line for better reliability and easier assembly and maintenance.

The initial KN93 offering is a standard compression 93 inch engine with authentic generator style crankcases for 1936-1947 Harley-Davidson® OHV big twin chassis.

KN-Series engines come completely assembled and ready to run with a preset S&S Super Stock™ electronic ignition system and Super E carburetor. KN-Series engines come with a 12 month warranty.

Alternator-Generator Style

Alternator/generator style KN-Series engines are very close in appearance to a stock knucklehead engine, but offer a number of modern features for more power, better engine life, and improved reliability.

Aside from the much larger 93 inch displacement, the main improvement in design is the 1958-1965 style flywheel assembly, which uses a splined sprocket shaft and Timken® sprocket shaft bearing, this necessitates the use of a 1955-1964 style inner tin primary cover and primary chain sprocket. S&S Vintage rocker arm cover tins are another modern improvement.

The KN93 is a standard compression 93 engine and is available with authentic generator style crankcases for early style chassis, primary and transmissions, and with alternator/generator style cases for use with 1970 and later primary covers and late style transmissions.

Fitment:

  • KN74
  • 1936-‘99 chassis
  • KN93
  • 1936-’47 stock chassis – will fit in 1948-'65 chassis with front motor mount spacer (included)
  • 1970-’99 Alternator/generator and alternator custom versions, custom bikes with 1970-’99 alternator style primary
  • KN-Kone
  • 1970-’98 big twin
  • 1999 chassis originally equipped with a Harley-Davidson® Evolution® engine
  • Can also be installed in earlier chassis if a transmission with a 1970-up main shaft is used

 

Features and Benefits:

  • Natural crankcases and black powder coated cylinders and heads
  • S&S Super E
  • S&S valve train – solid lifters
  • S&S Super Stock™ single fire ignition system and polished billet timer
  • 1936-‘47 models have correct length sprocket shaft for stock primary and transmission
  • Alternator and alternator/generator models have correct sprocket length sprocket shaft for 1970-up primary and transmission
  • Alternator/generator engines include oil filter mount for generator location
  • Alternator style crankcase – allows the use of modern primary, transmission, clutch components and electrical system
  • One-year warranty

 

KN-Series Engine Specifications

Engine Name
Displacement
Bore
Stroke
Carb
Cam
Piston Type
Compression Ratio
KN74 74" 3 7/16" 3 31/32" Super E 346 S&S Forged 7.5:1
KN93 93" 3 5/8" 4 1/2" Super E 420 S&S Forged 8.2:1
KN-Kone 93" 3 5/8" 4 1/2" Super E 420 S&S Forged 8.2:1

KN-Series Engines

Description
Part Number
KN74 Generator Style 310-0025
KN93 Generator Style 106-2161
KN93 Alternator/Generator Style 106-2560
KN-Kone Alternator Style 310-0006