S&S Cycle 910-0843A Big Bore Cylinder Kit Wrinkle Black Highlighted Fins - 129 M8

The S&S Cycle 910-0843A cylinder kit delivers maximum displacement increase for Harley-Davidson Milwaukee-Eight engines without requiring any crankcase machining. This bolt-on big bore kit increases 107" M8 engines to 129" and 114" engines to 132" using a 4.320" bore diameter with 4.375" stroke.

Key Features:

• 4.320" bore diameter with 11.0:1 compression ratio forged pistons
• Drop-in installation with stock crankcase compatibility—no case boring required
• Wrinkle black finish with highlighted cooling fins
• MLS (multi-layered steel) head gaskets for superior sealing
• Retains stock engine height and original engine serial numbers
• Stock bolt pattern for direct replacement
• Includes all necessary gaskets and hardware for installation

This kit includes cylinders, pistons, rings, and gaskets (head, base, and exhaust). Professional installation by a skilled technician is required to verify all clearances and assembly specifications. Aftermarket tuning is highly recommended to optimize performance with the increased displacement. Made in the USA.