129" Cylinder Kit - 4.375" Stroke - Wrinkle Black w/Highlighted Fins - M8 Original engine serial numbers are retained, MLS (Multi-Layered Steel) head gaskets, Retains stock engine height, Stock bolt pattern, Works with stock crankcase., Not compatible with VVT models.
The S&S Cycle 129" Big Bore Cylinder Kit is the easiest way to turn your Milwaukee-Eight 107 into a serious 129 cubic inch motor. This wrinkle black version with non-highlighted fins gives your bike a clean, factory look while delivering major performance gains.
Unlike the 136" kit, this 129" version is a true bolt-on — it uses your stock 4.375" flywheel, so no extra flywheel purchase is needed. It includes 4.320" cylinders, forged pistons, MLS head gaskets, and all required hardware.
Important Notes:
- Does not require the S&S 4-5/8" stroker flywheel
- Not compatible with Variable Valve Timing (VVT) models
- Retains stock engine height and original serial numbers
- Not legal for use on pollution-controlled vehicles in California
Fitment: Fits 2017-2026 Milwaukee-Eight Touring models (Road Glide, Street Glide, Electra Glide, etc.) and 2018-2026 Softail models with 107" engines.
