Harley-Davidson Low Rider S Big Bore Kits

Genuine Harley-Davidson

This kit was developed for the budget minded rider who wants to experience an adrenalin-pumping burst of speed on the way to the red line. The additional power starts to build at 3000 RPM and increases by up to 24% at the red line. When riding aggressively, you must downshift to lower gears to keep the engine in the higher RPM range. Ideal for riders looking for excitement and willing to ride in the upper RPM range. Produces greater acceleration in the mid and upper RPM range. Minimally invasive, requiring only the opening of the cam chest. Retains Original Equipment Factory Warranty. Includes covers in gloss black. Stage II Upgrade.

Genuine Harley-Davidson

Go big or go home. With the largest displacement of any Harley-Davidson Stage Kit, this 107CI to 128CI Stage IV Kit is designed to deliver maximum horsepower - all the way to the redline. Packaged with patent-protected cylinder technology, it allows for the largest bolt-on engine upgrade to any Milwaukee-Eight motor. Features new CNC-ported heads with 1mm bigger valves and fully machined combustion chambers. Coupled with the kit's high-lift SE8-517 cam, high compression pistons and a 64mm throttle body and intake manifold, this combination delivers a thrilling 135 ft-lb of torque and 124 HP rear-wheel output when paired with Screamin' Eagle Street Cannon Mufflers for 131 kit customers. It's designed to run wide open at high-end RPMs and provide a significant boost of torque from cruising speed. You'll feel the difference as soon as you twist the throttle. Delivers increased response throughout the entire RPM range. Provides thrilling acceleration when twisting the throttle. Maintains flat torque curve from cruising RPM to redline. Can be installed without removing the engine from chassis. Includes CNC Ported Cylinder Head with CNC machined chamber and 1mm larger valves, 131 Stage IV Timer cover, SE8-517 High-Lift Cam, Forged High Compression Pistons. Also includes High Performance Cam Bearing and High Performance Tappets, 4.31" Steel Sleeve Cylinders, 64mm Throttle Body and Cast Manifold, High Flow Injectors (5.5 g/sec). Pending 49-State U.S. EPA compliant.

Genuine Harley-Davidson

Screamin' Eagle Stage IV Kit - 117CI to 131CI

Genuine Harley-Davidson

This Stage IV Kit was developed to deliver maximum horsepower from the Milwaukee-Eight engine - all the way to the redline. The system-matched combination of larger displacement cylinders, free flowing CNC-Ported cylinder heads and a cam with the highest available valve lift are the starting point to building the perfect engine for the performance junkie. Designed for a high level of flexibility, this package is ideal for riders who like to comfortably cruise at lower rpm but still have plenty of arm-pulling acceleration when you whack the throttle. Kit includes CNC Ported Cylinder Heads with Performance Valve Springs, 64mm Throttle Body, High Flow Injectors (5.5g/s), 4.075" Bolt-On Cylinders, Forged 11:1 High Compression Aluminum Coated Pistons and Rings, SE8-515 Cam, Cam Bearing Upgrade, High Performance Tappets, Multi-layer Coated Head Gaskets, High Capacity Clutch Springs (1200N) and most necessary gaskets and seals. Increases power by up to 40% when compared to the Original Equipment engine configurations. Delivers increased response throughout the entire RPM range. Maintains flat torque curve from cruising RPM to redline. Can be installed without removing the engine from the chassis. Retains Original Equipment Factory Warranty. 50-State U.S. EPA compliant. Includes Screamin' Eagle Cylinder Heads with Performance Valve Springs, Throttle Body, High Flow Injectors, Bolt-On Cylinders, Pistons, Piston Rings, Cam, Cam Bearings, Tappets, Head Gaskets, Top End, Cylinder Base and Cam Cover Gaskets, and Clutch Springs.

Genuine Harley-Davidson

This kit was developed for the budget minded rider that wants to experience that adrenalin-pumping burst of speed while heading toward the red line. The additional power starts to build @ 3000 RPM and continues to build by up to 24% at redline. Riding the bike aggressively will require downshifting to lower gears to keep the engine operating in the higher RPM range. Ideal for riders looking for excitement and are willing to ride in the upper RPM range. Produces greater acceleration in the mid and upper RPM range. Minimally invasive, only requiring opening of the cam chest. Retains Original Equipment Factory Warranty. 50-State U.S. EPA compliant.

Genuine Harley-Davidson

This kit was developed for the budget minded rider that wants to experience crisp throttle response and acceleration they can feel at slower speeds. The 5% increase in torque can be felt immediately off the line and continues to build by up to a 14% increase @ 4500 RPM - the ideal power band for passing slow moving vehicles. Delivers enhanced torque and horsepower in the low to mid RPM range. Produces passing power without a downshift or high revs. Minimally invasive, only requiring opening of the cam chest. Retains Original Equipment Factory Warranty. Includes Gloss Black covers. Stage II Upgrade.

Genuine Harley-Davidson

This Stage IV Kit was developed to deliver maximum horsepower from the Milwaukee-Eight engine - all the way to the redline. The system-matched combination of larger displacement cylinders, free flowing CNC-Ported cylinder heads and a cam with the highest available valve lift are the starting point to building the perfect engine for the performance junkie.

Genuine Harley-Davidson

This kit was developed for the budget minded rider that wants to experience crisp throttle response and acceleration they can feel at slower speeds. The 5% increase in torque can be felt immediately off the line and continues to build by up to a 14% increase @ 4500 RPM - the ideal power band for passing slow moving vehicles. Delivers enhanced torque and horsepower in the low to mid RPM range. Produces passing power without a downshift or high revs. Minimally invasive, only requiring opening of the cam chest. Retains Original Equipment Factory Warranty. 50-State U.S. EPA compliant.

Genuine Harley-Davidson

Go big or go home. With the largest displacement of any Harley-Davidson Stage Kit, this 107CI to 128CI Stage IV Kit is designed to deliver maximum horsepower - all the way to the redline. Packaged with patent-protected cylinder technology, it allows for the largest bolt-on engine upgrade to any Milwaukee-Eight motor. Features new CNC-ported heads with 1mm bigger valves and fully machined combustion chambers. It's designed to run wide open at high-end RPMs and provide a significant boost of torque from cruising speed. You'll feel the difference as soon as you twist the throttle. Delivers increased response throughout the entire RPM range. Provides thrilling acceleration when twisting the throttle. Maintains flat torque curve from cruising RPM to redline. Can be installed without removing the engine from chassis. Includes CNC Ported Cylinder Head with CNC machined chamber and 1mm larger valves, 128 Stage IV Timer cover, SE8-517 High-Lift Cam, Forged High Compression Pistons. Also includes High Performance Cam Bearing and High Performance Tappets, 4.31" Steel Sleeve Cylinders, 64mm Throttle Body and Cast Manifold, High Flow Injectors (5.5 g/sec). Pending 49-State U.S. EPA compliant.