S&S Cycle MK136B Black Edition Engine Fits Harley-Davidson Oil-Cooled M8 Softail 2018-2024
Step up to a complete 136 cubic-inch Milwaukee-Eight powerplant built and assembled in Viola, Wisconsin, ready to drop into your oil-cooled Softail chassis. The MK136B transforms a stock M8 Softail into a big-inch performer with the kind of mid-range thump and high-rpm reach that has defined S&S crate engines for decades.
Key Features
- Complete 136 cubic-inch (2,228 cc) Milwaukee-Eight long-block assembly on Softail-specific S&S MKB-Series crankcases
- Patented dual-spray piston cooling jets, precision oil scraper, enlarged oil sump, and contoured oil-return floor
- High-flow cylinder heads with +1 mm oversize intake and exhaust valves, valves .030 inch longer than stock, and .605 inch max-lift springs
- S&S exclusive breather boxes, S&S performance oil pump, performance cam support plate, premium tappets with tappet cuffs, and forged pistons
- Available with the 475G gear-drive camshaft and a locked 49-state emissions calibration, or the 550G gear-drive race-only camshaft for closed-course competition use
- Billet aluminum covers, Champion spark plugs, sprocket-shaft spacer, and cam-cover badge included
- Factory-match black powder-coat finish; retains stock engine height for a direct chassis fit
- One-year S&S parts warranty
Technical Specifications
- Displacement: 136 cubic inches (2,228 cc)
- Crankcases: S&S MKB-Series, Softail-specific
- Cylinder Heads: High-flow alloy, +1 mm intake/exhaust valves, .030 inch longer than stock, .605 inch max-lift springs
- Pistons: Forged, dual-spray cooling jets
- Camshaft (475G *49 State): Gear-drive, 49-state calibration
- Camshaft (550G *Race Only): Gear-drive, closed-course grind
- Oil System: S&S performance oil pump, enlarged sump, contoured return
- Tappets: Premium with tappet cuffs
- Covers: Billet aluminum
- Finish: Factory-match black powder-coat (Black Edition)
- Engine Height: Retains stock
- Warranty: 1 year parts only
- Country of Origin: United States (Viola, Wisconsin)
Fitment Notes
- Compatible with Harley-Davidson 2018-2024 oil-cooled Milwaukee-Eight Softail chassis when the 550G race-only camshaft variation is selected; 2018-2020 oil-cooled Softail for the 475G 49-state variation.
- Excludes all water-cooled (Twin-Cooled) Softail variants.
- The 475G 49-state variation requires the complete S&S-specified combination for emissions compliance: stock H-D throttle body and injectors, S&S Stealth air cleaner, stock catalyst header with S&S-specified mufflers, and the locked S&S DJT calibration flashed via a Dynojet PV-3 or PV-4 (tuner sold separately).
- The 550G race-only variation ships without an emissions calibration; chassis-side ECM tuning is the installer’s responsibility and a Dynojet PV-3 or PV-4 is the typical tuning route.
- Refer to the Fitment tab for the full year and model breakdown for each variation.
- Not affiliated with or endorsed by Harley-Davidson.
