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Tuesday 7 March 2023

H-D Screamin' Eagle

H-D Screamin' Eagle 135 Stage IV Crate Engine

Claimed to "set a new performance benchmark," Harley's new Stage IV performance Screamin' Eagle 135" crate engine (and wireless Pro Street performance tuner) is a "thrilling new option for Harley-Davidson riders craving no-compromise performance."

This complete M-8 engine for 2021-later Touring models "is the new benchmark for factory-engineered American V-Twin performance, offering the most displacement and the most power ever created by Harley-Davidson for a street-compliant crate engine. 

"The development was fueled in part by the efforts of the Harley-Davidson Screamin’ Eagle Factory racing team competing in the MotoAmerica Mission King Of The Baggers road racing series. 

"To simplify the set-up of high-performance engines, Harley-Davidson offers a new wireless Screamin’ Eagle Pro Street performance tuner, the only tuner available to maximize performance while being emissions and warranty-compliant.

'68 mm throttle body'

"Engineered and tested as a complete collection of high-performance components and assembled from the bottom up at Harley-Davidson Powertrain Operations in Menomonee Falls, Wisconsin, this street-tuned 135 cubic inch (2,212 cc) Screamin’ Eagle crate engine is designed to run with a wide-open throttle at high engine speeds and provide instant passing power from cruising speed. The engine delivers 143 lb/ft of rear-wheel torque at 3,500 rpm and 130 rear-wheel horsepower at 5,500 rpm - approximately 28% more torque and 41% more horsepower at the rear wheel than a production Milwaukee-Eight 117 engine."

Components include a new 68 mm throttle body and matching CNC-machined intake manifold, originally developed to maximize airflow in Screamin’ Eagle Factory racing team engines; Screamin' Eagle extreme CNC-ported cylinder heads that provide significantly improved efficiency of cylinder filling, leading to more power and increased rear-wheel torque when compared to stock, and high-performance valve springs that remain stable with the high-lift cam and when in high-rpm operation.

The Screamin' Eagle Pro billet cam plate and oil pump provides higher pressure when the oil is hot (to keep pressure drops to a minimum); there are new 10.7:1 high-compression forged pistons; SE8-517 high-lift camshaft, high-performance cam bearing and high-performance tappets; patent-protected 4.31 inch steel sleeve cylinders, new 4 5/8 inch flywheel (bore x stroke is 4.31 x 4.625) and new high-capacity 6.8 g/second fuel injectors.

Harley says that the Screamin’ Eagle ventilator extreme air cleaner and Screamin’ Eagle Street Cannon mufflers (each sold separately) are not required but are highly recommended for peak performance. 

Two versions of the engine will be offered: for 2021-later Touring models equipped with air/oil-cooled Milwaukee-Eight engine, and for 2021-later Touring models equipped with a twin-cooled Milwaukee-Eight engine. The engine does not fit Trike or California models. 

'Bagger Racing derived'

Installation requires the separate purchase of head pipe P/N 65600177. Air-cooled models require oil cooler fan assist P/N 62700204 or fan for Factory oil cooler P/N 26800195. All models require ECM recalibration with Screamin' Eagle Pro Street tuner for proper installation. 

The engine is intended for bolt-in installation in an original equipment-style 2021-later Harley-Davidson Touring chassis. No special fabrication or engine-mount relocation is required. The engine is backed by up to two-year manufacturer’s warranty when dealer-installed through the Custom Coverage program. MSRP is $7,999.95 and it is offered in black or chrome finish with 135 Stage IV badging on the cylinder heads and timer cover.