S&S Cycle 129" Big Bore Kit 4.375" Stroke for 107" M8 Models

The biggest Big Bore slip on kit available, S&S 129" Big Bore Kit for the 107" M8 Harley models. Choose between Highlighted and Non-Highlighted cylinders.

Fits: 2017-2022 M-Eight 107" Harley Models

• Bolt-on kit, the largest cylinder bore possible without required machining of the crankcases
• Huge bore increase means huge power increase
• Works with stock crankcases (no machine work)
• Powder coat finish matches factory finish
• MLS (multi-layered steel) head gaskets
• 4.320" Bore
• Retains stock engine height
• Includes Cubic Inch Cam Cover Badge
• Made in USA