S&S 310-1226D 129" 550 Big Bore Power Pack 18-26 107" Harley FL & Softail
- Big-bore bolt-on kit increases 107" M8 to 129" with no case machining required
- 4.32" bore cylinders with 11.0:1 compression ratio forged pistons
- S&S oil pump/cam plate with blue anodized finish
- Passage plugs are removable for servicing
- Independent scavenge sections for flywheel cavity and cam chest
- Debris screen in both scavenge pickups
- Magnet in cam chest to help prevent debris from entering the oil pump
- Increased oil flow capacity on both the oil feed and scavenge side
- Adjustable pressure relief valve can be adjusted with the unit installed in the engine
- Quickee pushrods
- S&S premium tappets
- S&S hard-anodized, black coated tappet cuffs are billet aluminum construction
- S&S 550 cams are designed for big bore applications
- S&S valve springs work with cams up to 0.605" lift
- High-performance conical single wire spring design
- Made in the USA
- Notes
- Will fit VVT models.
- Not for any Trike models.
- Intake/rocker cover gaskets not included.
| Product Name | Power Package |
| Style | 550C |
| Model | Performance Kit |
| Color/Finish | Non-Highlighted Fins / Wrinkle Black |
| Features | Black Pushrod Tubes / Cam Chain Tensioner |
| Stroke Length | 4.375" |
| Displacement | 129" |
| Bore Size | 4.320" |
| Compression Ratio | 11.0:1 |
| Cam Drive Type | Chain |
| Cooling System | Oil Cooled |
| Units | Kit |
| Riding Style | Street |
| 2026 | Harley-Davidson | FXBR Breakout 117 | - | - |
| 2025-2026 | Harley-Davidson | Softail Heritage Classic FLHC | - | - |
| 2025-2026 | Harley-Davidson | Softail Fat Boy FLFB | - | - |
| 2025 | Harley-Davidson | Street Glide EFI FLHX | - | - |
| 2025 | Harley-Davidson | Softail Breakout FXBR | - | - |
| 2020-2024 | Harley-Davidson | FXST Softail Standard 107 | - | - |
| 2018-2021 | Harley-Davidson | FLHC Heritage Classic 107 | - | - |
| 2018-2021 | Harley-Davidson | FLSL Softail Slim 107 | - | - |
| 2018-2021 | Harley-Davidson | FLSB Sport Glide 107 | - | - |
| 2018-2020 | Harley-Davidson | FLFB Fat Boy 107 | - | - |
| 2018-2020 | Harley-Davidson | FLDE Deluxe 107 | - | - |
| 2018-2020 | Harley-Davidson | FXBB Street Bob 107 | - | - |
| 2018-2020 | Harley-Davidson | FXLR Low Rider 107 | - | - |
| 2018-2019 | Harley-Davidson | FXBR Breakout 107 | - | - |
| 2018-2019 | Harley-Davidson | FXFB Fat Bob 107 | - | - |
| 2017-2026 | Harley-Davidson | FLHX Street Glide | - | - |
| 2017-2026 | Harley-Davidson | FLTRX Road Glide | - | - |
| 2017-2023 | Harley-Davidson | FLTRXS Road Glide Special | - | - |
| 2017-2023 | Harley-Davidson | FLHXS Street Glide Special | - | - |
| 2017-2022 | Harley-Davidson | FLHR Road King | - | - |
| 2017-2019 | Harley-Davidson | FLHRC Road King Classic | - | - |
