Harley Screamin' Eagle Piston Kit 4.310" Bore x 4.5" Stroke 2017-25 Touring,ST

Part number 21900099  a Screamin' Eagle High Compression Piston Kit from Harley-Davidson, designed for use in the 131CI Stage IV performance upgrades for Milwaukee-Eight engines. 

Product Details

The kit is a key component of the largest displacement bolt-on engine upgrade offered by Harley-Davidson, providing significant gains in torque and horsepower when installed as part of a complete Stage IV kit. 

Bore and Stroke: 4.310" bore x 4.5" stroke.

Material: Forged from high-strength aluminum.

Design: Features precision-machined, coated skirts for a tight tolerance fit and quieter operation. The piston design and rings are engineered to withstand increased combustion forces.

Kit Contents: Includes two pistons, rings, wrist pins, and clips.

Legal Status: These are 50-State U.S. EPA compliant for sale and use on all applicable

Fitments

The Screamin' Eagle part number 21900099 high-compression piston kit is a replacement part for Milwaukee-Eight engines that have been upgraded with a 131CI Stage IV performance kit.

Compatible Models

The pistons fit specific Harley-Davidson models that are already running the 131 cubic inch (4.310" bore x 4.5" stroke) Stage IV engine upgrade: 

Touring Models: Fits 2017–2025 Harley-Davidson Touring models equipped with 131CI Stage IV kits.

Excludes: 2023-later Center Cooled Touring models.

Excludes: Trike models.

Softail Models: Fits 2018–2024 Harley-Davidson Softail models equipped with 131CI Stage IV kits.

Excludes: 2025-later Softail models. 

Important Notes

Stage IV Requirement: This kit is designed as a replacement specifically for the 131CI Stage IV setup; it is not for use with 128CI or other kits.

Engine Control Module (ECM): All installations and replacements require an ECM calibration using a Screamin' Eagle Pro Street Tuner for proper operation.

Components: The kit is designed to work with other specific Screamin' Eagle components, such as the SE8-517 cam developed for these engines.

Selling as pictured.

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010826-JM7