S&S Cycle Conversion Kits — 1986-2021 Harley-Davidson Sportster Models

S&S Cycle 1250cc conversion kit for 1986–2021 Harley Sportster, upgrading stock 883cc and 1200cc displacement without requiring cylinder machining or piston rebalancing. Includes forged pistons, S&S cylinders, gasket set, and assembly lube.

Features

• Forged flat-top pistons with coated skirts
• S&S 3-9/16" bore cylinders
• Complete gasket set included (head, base, exhaust)
• No machining or rebalancing required
• Assembly lube and instructions included

Specifications

• Brand: S&S Cycle
• Manufacturer Part #: 910-0691
• Displacement Upgrade: 883cc or 1200cc to 1250cc
• Piston Bore: 3-9/16 inch
• Weight: 21.5 lb
• Category: Engine Components / Piston Sets - Powersports

Fitment

Fits 1986–2021 Harley-Davidson Sportster models. 883cc cylinder heads are not compatible with this kit and cannot be reused.

Frequently Asked Questions

Will this work with my 883 or 1200 Sportster?

Yes — this kit converts either displacement to 1250cc. However, 883 cylinder heads cannot be used and must be replaced.

Do I need to machine or rebalance the cylinders and pistons?

No — S&S designed this kit for bolt-on installation without machine work or rebalancing.

What's included in the box?

Forged pistons, S&S cylinders, head gasket, base gasket, exhaust gaskets, assembly lube, and installation instructions.

Will this kit alone give me the best performance?

The kit will increase displacement, but S&S recommends pairing it with CNC head porting, performance cams, exhaust, and intake upgrades for optimal results.