The S&S CYCLE MK-Series "B" Crankcase, manufacturer part number 310-1326, is a black crankcase designed for select Harley-Davidson M8 Softail applications. It features a stock deck height, a large-volume sump, and a machined, close-fitting oil scraper. The crankcase provides a solid foundation for building a big-bore engine while fitting into the stock Softail frame.
The close-fitting oil scraper helps scrape more oil, while the crankcase design supports reliability and allows installation of larger bore kits. It can be paired with an S&S 136-inch cylinder kit and a 4 5/8-inch stroker crank, which are sold separately. The product is made in the USA and includes a Manufacturer's Statement of Origin (MSO) document.
Vehicle fitment includes the 2022 and 2023 Harley-Davidson FXST Softail Standard 107; 2019 Harley-Davidson FXFB Fat Bob 107; 2019 and 2022 Harley-Davidson FLFBS Fat Boy 114; 2018, 2021, and 2024 Harley-Davidson FLHCS Heritage Classic 114; and 2018 and 2020 Harley-Davidson FXBB Street Bob 107. Distributor part number was not provided.
Features:
- Brand: S&S CYCLE
- Product: MK-Series "B" crankcase
- Color: Black
- Manufacturer Part Number: 310-1326
- Deck Height: Stock
- Sump: Large volume
- Oil Scraper: Machined, close-fitting design
- Application: Select Harley-Davidson M8 Softail models
- Engine Building: Provides a foundation for big-bore engine builds and allows installation of larger bore kits
- Fitment: 2022-2023 Harley-Davidson FXST Softail Standard 107; 2019 FXFB Fat Bob 107; 2019 and 2022 FLFBS Fat Boy 114; 2018, 2021, and 2024 FLHCS Heritage Classic 114; 2018 and 2020 FXBB Street Bob 107
- Additional Information: Can be paired with an S&S 136-inch cylinder kit and 4 5/8-inch stroker crank, sold separately
- Origin: Made in the USA
- Included Documentation: Manufacturer's Statement of Origin (MSO)
Fitment:
2018 Harley-Davidson FLDE Deluxe 107
2018 Harley-Davidson FLFB Fat Boy 107
2018 Harley-Davidson FLFBS Fat Boy 114
2018 Harley-Davidson FLHC Heritage Classic 107
2018 Harley-Davidson FLHCS Heritage Classic 114
2018 Harley-Davidson FLSB Sport Glide 107
2018 Harley-Davidson FLSL Softail Slim 107
2018 Harley-Davidson FXBB Street Bob 107
2018 Harley-Davidson FXBR Breakout 107
2018 Harley-Davidson FXBRS Breakout 114
2018 Harley-Davidson FXFB Fat Bob 107
2018 Harley-Davidson FXFBS Fat Bob 114
2018 Harley-Davidson FXLR Low Rider 107
2019 Harley-Davidson FLDE Deluxe 107
2019 Harley-Davidson FLFB Fat Boy 107
2019 Harley-Davidson FLFBS Fat Boy 114
2019 Harley-Davidson FLHC Heritage Classic 107
2019 Harley-Davidson FLHCS Heritage Classic 114
2019 Harley-Davidson FLSB Sport Glide 107
2019 Harley-Davidson FLSL Softail Slim 107
2019 Harley-Davidson FXBB Street Bob 107
2019 Harley-Davidson FXBR Breakout 107
2019 Harley-Davidson FXBRS Breakout 114
2019 Harley-Davidson FXDRS FXDR 114
2019 Harley-Davidson FXFB Fat Bob 107
2019 Harley-Davidson FXFBS Fat Bob 114
2019 Harley-Davidson FXLR Low Rider 107
2020 Harley-Davidson FLDE Deluxe 107
2020 Harley-Davidson FLFBS Fat Boy 114
2020 Harley-Davidson FLHC Heritage Classic 107
2020 Harley-Davidson FLHCS Heritage Classic 114
2020 Harley-Davidson FLSB Sport Glide 107
2020 Harley-Davidson FLSL Softail Slim 107
2020 Harley-Davidson FXBB Street Bob 107
2020 Harley-Davidson FXBRS Breakout 114
2020 Harley-Davidson FXDRS FXDR 114
2020 Harley-Davidson FXFBS Fat Bob 114
2020 Harley-Davidson FXLR Low Rider 107
2020 Harley-Davidson FXLRS Low Rider S 114
2020 Harley-Davidson FXST Softail Standard 107
2021 Harley-Davidson FLFBS Fat Boy 114
2021 Harley-Davidson FLHC Heritage Classic 107
2021 Harley-Davidson FLHCS Heritage Classic 114
2021 Harley-Davidson FLSB Sport Glide 107
2021 Harley-Davidson FLSL Softail Slim 107
2021 Harley-Davidson FXBBS Street Bob 114
2021 Harley-Davidson FXFBS Fat Bob 114
2021 Harley-Davidson FXLRS Low Rider S 114
2021 Harley-Davidson FXST Softail Standard 107
2022 Harley-Davidson FLFBS Fat Boy 114
2022 Harley-Davidson FLHCS Heritage Classic 114
2022 Harley-Davidson FXBBS Street Bob 114
2022 Harley-Davidson FXLRS Low Rider S 117
2022 Harley-Davidson FXLRST Low Rider ST 117
2022 Harley-Davidson FXRST Low Rider El Diablo 117
2022 Harley-Davidson FXST Softail Standard 107
2022 Harley-Davidson Softail Street Bob FXBB
2023 Harley-Davidson FLFBS Fat Boy 114
2023 Harley-Davidson FLHCS Heritage Classic 114
2023 Harley-Davidson FXBBS Street Bob 114
2023 Harley-Davidson FXBR Breakout 117
2023 Harley-Davidson FXFBS Fat Bob 114
2023 Harley-Davidson FXLRS Low Rider S 117
2023 Harley-Davidson FXLRST Low Rider ST 117
2023 Harley-Davidson FXST Softail Standard 107
2024 Harley-Davidson FLFBS Fat Boy 114
2024 Harley-Davidson FLHCS Heritage Classic 114
2024 Harley-Davidson FXBBS Street Bob 114
2024 Harley-Davidson FXBR Breakout 117
2024 Harley-Davidson FXLRS Low Rider S 117
2024 Harley-Davidson FXLRST Low Rider ST 117
2024 Harley-Davidson FXST Softail Standard 107