Rocket Performance Garage Llc Big Bore Cylinder Kits - KIT 124" M8 2017-2024 (e… — Harley-Davidson (2017-2024)

Rocket Performance Garage 124 cubic-inch big-bore cylinder kit for 2017-2024 Harley Milwaukee-Eight engines, displacing the stock M8 to 124cc with premium USA-cast cylinders and CP forged pistons. Increases displacement and compression for measurable power gains without major engine teardown.

Features

• USA-cast premium cylinders with textured black powdercoat
• CP forged pistons included
• 4.375 in stroke
• 10.5:1 compression ratio
• Machined fins for stock OEM appearance

Specifications

• Brand: Rocket Performance Garage
• Manufacturer Part #: 8-8101
• Displacement: 124 cubic inches
• Compression Ratio: 10.5:1
• Piston Brand: CP (forged)
• Length: 9 in
• Width: 8 in
• Height: 20 in
• Weight: 25 lbs
• Country of Origin: USA

Fitment

Fits 2017-2024 Harley-Davidson Milwaukee-Eight (M8) engine platforms.

Frequently Asked Questions

Will this kit fit older Harley engines like the Twin Cam?

No — this kit is engineered specifically for 2017-2024 Milwaukee-Eight engines. Twin Cam and earlier platform engines require different big-bore kits.

What compression ratio does this achieve?

10.5:1 compression, which is designed to work with 91-octane fuel and OEM Harley fuel management on stock M8 bikes.

Are the cylinders and pistons matched?

Yes. The cylinders are precisely fitted and matched to the included CP forged pistons for proper clearance and performance.

Do I need a professional engine builder to install this?

Big-bore kits require cylinder head removal and careful machining. Professional installation is strongly recommended to ensure proper fitment and sealing.