S&S Cycle 910-0690 1250cc Big Bore Conversion Kit Silver

The S&S Cycle 910-0690 is a complete big bore conversion kit designed to transform 1986-2021 Harley-Davidson Sportster 883cc and 1200cc models into high-performance 1250cc machines. This bolt-in kit delivers increased displacement and power without requiring extensive machining or engine removal, making it an ideal upgrade for riders seeking more performance from their Sportster.

Complete Kit Includes:

• S&S 1250cc forged pistons with rings and wristpins
• S&S 3-9/16" bore cylinders with silver finish
• MLS (Multi-Layer Steel) head, base, and exhaust gaskets
• Assembly lube and detailed installation instructions

Key Features:

• Forged pistons feature coated skirts with measurement window and S&S logo
• Enlarged valve pockets accept valves up to 2.00" diameter
• 3.562" (3-9/16") bore size with 11.2:1 compression ratio
• Domed piston design for optimal combustion efficiency
• Constructed from high-quality iron and aluminum materials
• Made in the USA with S&S's renowned quality standards

Important Notes:

• This kit will NOT work with XR1200 models
• 883cc models will require XL1200 cylinder heads to achieve correct compression ratios
• Designed for street riding applications

S&S Cycle has been the leader in Harley-Davidson performance parts for decades, and this 1250cc conversion kit represents their commitment to quality engineering and proven performance gains. The bolt-in design simplifies installation while the forged pistons and precision-machined cylinders ensure durability and reliability for thousands of miles of spirited riding.