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