The Screamin’ Eagle Stage IV kit 92500146 takes the specified Softail engine from 117ci to 131ci as a coordinated engine upgrade. Harley-Davidson describes it as a package for riders seeking greater displacement, compression and power-to-weight performance. Its catalogue says many of the components were informed by Factory Racing Team testing for King of the Baggers; that does not mean the complete retail kit is a race-winning specification for your bike.
The package brings together Screamin’ Eagle Extreme CNC-ported cylinder heads, a 68 mm throttle body and a cast 68 mm intake manifold. The SE8-550 high-lift cam and 6.8 g/sec fuel injectors work with that intake to supply air and fuel. Forged high-compression pistons and rings are designed for the increased combustion forces, alongside high-performance tappets and patent-protected 4.31-inch steel-sleeve cylinders. These are complementary engine components, rather than an intake accessory or a generic set of builder parts.
H-D describes the combination as intended for wide-open throttle and higher rpm, with a substantial torque increase when accelerating from cruising speed. Those are manufacturer performance claims, not a measured power or torque result for your motorcycle. The Black Highlighted kit adds Screamin’ Eagle and Stage IV badging to the cylinder heads and timer cover. H-D also states that installation can be completed with the engine still in the chassis; it does not describe this as a simple owner installation.
The exact listing specifies 2025-on Softail models, excludes California models and requires ECM recalibration with the Screamin’ Eagle Pro Street Tuner. This is the particular 117ci-to-131ci kit shown in the film. Confirm your motorcycle, installation requirements and local availability with the exact product information and dealer. H-D explicitly notes that these products are not sold or approved for road use in every country.
