• Huge displacement increase means huge power increase
  Stock crankcases, cylinder heads, oil pump, and cam cover can be reused, saving hundreds of dollars
• Original engine serial numbers are retained
• Gear drive S&S 640GE Easy Start Cams included
• Black powder-coat finish heads match factory finish, giving bike a "sleeper" advantage
• .045" MLS (multi-layered steel) head gaskets
• Requires crankcase boring 
• Adds .096" to engine height
• Kits with S&S® heads use stock length manifolds (S&S size 405)
• Kit includes S&S® Super Stock® 91cc Cylinder Heads
• 10.8:1 Compression Ratio
• Cylinder w/ piston kits include fitted flat top pistons ready to install
• 4 5/8" Stroke
• 4 1/8" Bore
• 5.004" Cylinder bore
• Made in the U.S.A.
• Not for Twin Cooled models

NOTE: This project requires a skilled technician. It is the responsibility of the person assembling the parts to check all clearances and assembly specifications

NOTES:

Stock crankcases need to be bored to accept new 4 1/8" bore cylinders

S&S Easy Start Cams save you money – no need to buy compression releases or S&S rocker covers.

For engines with cable controlled throttle bodies we recommend the S&S 58mm single bore throttle bodies and manifolds.

For 2008-up touring models with electronic throttle control S&S recommends a S&S Throttle Hog 58mm or 66mm Throttle body 

Main Bearing Note: S&S flywheel assemblies included in a 124” S&S Hot Set Up Kit® for 1999-'15 Big Twin engines are designed for use with Timken® sprocket shaft bearings.
They will fit directly in stock 1999-’02 Harley-Davidson® crankcases and in all S&S crankcases for 1999-'15 Big Twin engines, with no modifications. However, stock
2003 and later engines use a roller type bearing for the sprocket shaft, and will require modification.

Due to the amount of power these engines produce with an S&S Hot Set Up Kit, S&S strongly recommends retrofitting 2003-'15 model crankcases to accept a Timken
sprocket shaft bearing. A Timken conversion sleeve such as Screamin' Eagle® #34822-08 or Jim's® #956 may be used. A charging system spacer for 1999-'02 model year is
also required.

If you choose not to convert your crankcases to a Timken sprocket shaft bearing, S&S flywheels may be used in 2003 and later engines with the installation of the Harley-
Davidson® bearing kit #24004-03B. This bearing kit adapts the S&S sprocket shaft to be compatible with stock roller type bearings. Verify that the bearing kit contains
the 24604-00D or 24607-07 sprocket shaft bearing. Do not use a 24604-00, 24604-00A, 24604-00B or 24604-00C bearing. Please be advised that if this type of bearing is
used, sprocket shaft bearing failure WILL NOT be covered under warranty.
Fuel injection tuning is required. 

Kits with S&S heads are machined special to compensate for engine height change to accommodate a stock length manifold.

The Air Resources Board (ARB) does not permit the use of aftermarket emission-related parts that alter the air/fuel ratio of an emission-controlled vehicle. Due to these legal restrictions this part cannot be shipped to California.