✓ VERIFIED
Jun 21, 2017
product is shipped without crankcase ventilation parts that are clearly part of kit.
S&S CYCLE
SKU: T14-662691
S&S Cycle 1250cc Big Bore Conversion Kit - Harley Sportster
$1,008.95
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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.
Unleash serious power from your Harley Sportster with the S&S Cycle 1250cc Conversion Kit. This kit transforms your 883cc or 1200cc engine into a potent 1250cc powerplant, delivering a noticeable increase in displacement and torque. Designed for a straightforward installation, it's a direct path to enhanced performance.
Why riders pick this
- Converts 883cc or 1200cc Sportster to 1250cc
- Forged flat-top pistons with coated skirts
- Includes cylinders, gaskets, and assembly lube
- No machining or rebalancing required for installation
- Designed for a significant power and torque boost
This S&S Cycle 1250cc conversion kit is engineered to provide a substantial displacement upgrade for your Harley Sportster. It's a comprehensive package that includes all the critical components needed to bump your engine size, creating more usable power across the RPM range. Built with performance and durability in mind, this kit is a popular choice for riders looking to uncork their Sportster.
Effortless Power Upgrade
- Increases displacement from 883cc or 1200cc to 1250cc
- Forged flat-top pistons with coated skirts for improved wear
- Includes S&S 3-9/16" bore cylinders and a complete gasket set
- Designed for installation without requiring machine work or piston rebalancing
- Comes with assembly lube and detailed instructions for a smooth build
Built for the Road
The S&S Cycle 1250cc Conversion Kit is more than just a size increase; it's a foundation for a more responsive and powerful ride. While it's designed for a straightforward bolt-on process, remember that 883cc cylinder heads are not compatible and will require an upgrade to a 1200cc or performance head. This kit is ideal for Sportster owners chasing that extra grunt and a more exhilarating riding experience.
Specifications
- Brand: S&S Cycle
- Manufacturer Part #: 910-0689
- Displacement Increase: 883cc or 1200cc to 1250cc
- Piston Bore: 3-9/16 inch
- Weight: 22.1 lb
- Category: Engine Components / Piston Sets - Powersports
Common questions
Can I use my stock 883 cylinder heads with this kit?
No, the 883cc cylinder heads are not compatible with this 1250cc conversion kit. You will need to upgrade to 1200cc heads or a performance aftermarket head.
Does this kit require any specialized machine work?
No, this S&S Cycle conversion kit is designed for a direct bolt-on installation, meaning no machining or piston rebalancing is required for the cylinders and pistons.
Will I need to retune my Sportster after installing this kit?
Yes, increasing your engine's displacement will require a proper dyno tune to optimize fuel delivery and ignition timing for the new setup. This ensures maximum performance and engine longevity.
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 | Piston Sets - Powersports |
| SKU | T14-662691 |
| WEIGHT | 22.1 lb |
Please contact us to confirm fitment for your specific motorcycle, or check the product title for compatibility notes.
CUSTOMER REVIEWS
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✓ VERIFIED
Nov 6, 2025
After much fabrication and alternative parts, it is installed. Not having a manifold ported for a map sensor complicates things significantly. I wasn’t going to settle for some pro rated refund because it was out of box. Much work left to do, but I’m committed to making it work.
✓ VERIFIED
Aug 5, 2022
Havent put it on yet but if its as good as the customer service i recieved getting the carb itll be breezy!
✓ VERIFIED
Apr 8, 2021
Fast shipping and it is in stalled runs great
✓ VERIFIED
Dec 3, 2020
Carb was installed per the O.E.M. Instructions, set-up and it runs and performs better than new! The JP Cycle online order was perfect!
✓ VERIFIED
Sep 14, 2020
I love the upgraded carburetor and intake system S&S .. great product and great addition too my harley.
