S&S Cycle MK-Series Crankcases - Harley Milwaukee-Eight Touring
About S&S Cycle
S&S Cycle has built American V-twin performance parts in Viola, Wisconsin since 1958 — flywheels, carburetors, cams, cylinder heads and complete crate engines. When a Harley owner talks about a 124, a 128 or a 131 build, they are usually talking about S&S. Few names carry more weight with engine builders in this space.
S&S Cycle MK-Series crankcases are engineered for Harley-Davidson Milwaukee-Eight Touring models, specifically designed to support larger-displacement engine builds. These cases provide a robust foundation for high-output power without requiring any frame modifications.
Why riders pick this
- Supports large-displacement builds up to 4.5-inch bore
- Improved oil scavenging with machined oil scraper
- Large-volume oil sump for better cooling and reliability
- Maintains OEM geometry, no frame modifications needed
When you're pushing the limits of your Milwaukee-Eight engine, a strong foundation is non-negotiable. S&S Cycle MK-Series crankcases are built for performance, featuring a redesigned spigot bore that accommodates cylinders up to a 4.5-inch bore. This allows for significant displacement increases, unlocking serious power potential for your Touring bike.
Engineered for High-Output Builds
- Redesigned spigot bore accepts cylinders up to 4.5-inch bore
- Machined, close-fitting oil scraper for improved scavenging
- Large-volume oil sump enhances cooling and reliability
- Maintains stock deck height for OEM geometry
Unleash More Power
The MK-Series crankcases are not just about raw strength; they're also designed for enhanced reliability under stress. The machined oil scraper improves scavenging compared to stock cast cases, and the large-volume oil sump aids in cooling, critical for high-performance applications. Best of all, these cases install without needing any frame modifications, making your big-displacement build more straightforward.
Specifications
- Brand: S&S Cycle
- Manufacturer Part #: 310-1341
- Category: Engine Components / Crankshafts
- Weight: 31.65 lb
Common questions
Can these crankcases support a 4.5-inch bore cylinder kit?
Yes, the 4.695-inch spigot bore is specifically designed to accept cylinder kits up to a 4.5-inch bore, enabling substantial big-displacement builds.
Will I need to modify my frame to install these crankcases?
No, these S&S Cycle crankcases maintain the stock deck height, which means they install directly into your Harley-Davidson Touring model without requiring any frame modifications.
What is the benefit of the machined oil scraper?
The machined, close-fitting oil scraper provides better oil scavenging compared to standard cast cases, contributing to improved engine performance and longevity under high-output conditions.
Ordering from Vtwinbikers
- Brand new, sourced through authorized US distribution — never used, never grey-market.
- Not sure it fits? Use Shop by Bike to filter by your year and model, or email us and we will confirm before you order.
- Harley-Davidson and Indian Motorcycle is all we do, so you are talking to people who ride what you ride.
| BRAND | S&S Cycle |
| TYPE | Crankshafts |
| SKU | T14-1025445 |
| WEIGHT | 31.65 lb |