Harley Unleashes Screamin' Eagle 135ci Stage IV Crate Engine

Tens of millions of dollars and countless man-hours go into Harley-Davidson's King of the Baggers operation. None of those resources go to waste, either, with the Motor Company snatching the KotB crown in 2021 and nearly repeating in 2022. The fruits of the race team’s labor go beyond the circuit as well, with H-D engineers and designers fashioning race-developed parts for brand faithful.

Now, Harley brings even more KotB-proven performance to the market with its Screamin' Eagle 135ci Stage IV crate engine. The new top-dog Milwaukee-Eight V-twin features the same 68mm throttle body and CNC-machined intake manifold originally designed for Kyle and Travis Wyman’s championship-contending Road Glide Special. Screamin' Eagle Extreme CNC-ported cylinder heads, high-performance valve spring, and an SE8-517 high-lift camshaft take full advantage of the V-twin's larger 2,212cc volume.

Forged pistons shoot through 4.31-inch steel-sleeve cylinders with 4.625 inches of stroke. The 4 5/8-inch flywheel steadies the big-bore M8, while the Screamin' Eagle Pro Billet Cam Plate and Oil Pump maintain optimal oil pressure. With a 10.7:1 compression ratio and high-flow fuel injectors (6.8 grams/second), the 135 crate engine lays down 143 lb-ft of torque (at 3,500 rpm) and 130 horsepower (at 5500 rpm)—all at the rear wheel.

That output eclipses the Bar and Shield’s largest production engine, the Milwaukee-Eight 117, by 28 percent in the torque department and 41 percent in pony power. Harley-Davidson recommends pairing the Stage IV Milwaukee-Eight with Screamin’ Eagle Ventilator Extreme Air Cleaner and Screamin’ Eagle Street Cannon mufflers to achieve those reported power figures.

Retailing for $7,999.95, the Screamin' Eagle 135ci Stage IV Performance Crate Engine comes in a Black or Chrome finish and is compatible with 2021 and later Touring models (sans Trikes). The brand also offers the crate engine in Air/Oil-Cooled and Twin-Cooled configurations.

To retain emissions and warranty compliance, the installation also requires ECM recalibration with the Screamin' Eagle Pro Street Tuner. Of course, 135 Stage IV badging on the cylinder heads and timer cover lets everyone know that your Hog benefits from KotB-derived performance.

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