Rocket Performance Garage Llc Big Bore Cylinder Kits - KIT 128" M8 2017-2024 (e… — Harley-Davidson (2017-2024)

Rocket Performance Garage 128cc big bore cylinder kit for 2017-2024 Harley Milwaukee-Eight engines, displacing the M8 from 107cc to 128cc. Includes USA-made cylinders and Wiseco forged pistons matched for reliable power gains and street rideability.

Features

• Increases M8 displacement to 128cc
• 10.5:1 compression ratio
• Wiseco forged pistons included
• USA-manufactured cylinders
• Black powder-coated finish with machined fins

Specifications

• Brand: Rocket Performance Garage
• Manufacturer Part #: 8-8102
• Displacement Increase: 107cc to 128cc
• Compression Ratio: 10.5:1
• Piston Type: Wiseco 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) engines.

Frequently Asked Questions

What displacement does this kit bring my M8 to?

This kit displaces your 2017-2024 Milwaukee-Eight from 107cc to 128cc total.

Is professional installation required?

Yes — big bore cylinder installation requires engine disassembly and precise machine work. Have a qualified Harley technician or performance shop handle this job.

Will I need to tune my bike after installation?

Yes — a fuel and ignition tune via ECM flash or aftermarket tuner is strongly recommended to optimize the extra displacement and compression.

Are these cylinders street-legal?

These are performance parts. Check your local emissions regulations before installation — some jurisdictions may require emissions testing.

What's included in the kit?

The kit includes the big bore cylinders and Wiseco forged pistons. Head gaskets, base gaskets, and other sealing components are typically sold separately.