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S&S Cycle 1250 Big Bore Kit For Harley Sportster 1986-2022

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This item is available as a Blem/Refurb. These are items that cannot be sold as "New" merchandise and are limited to stock on hand. See the product details for a description of the product's condition.

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This product is legal in California only for racing vehicles which may never be used, registered or licensed for use upon a highway.

S&S Cycle 1250 Big Bore Kit For Harley Sportster 1986-2022 Resources

S&S 1250 Big Bore Kit For Harley Sportster 

This kit converts 1200cc HD Sportster models to 1250cc displacement. No machining or rebalancing is required. Forged pistons have larger than stock valve pockets and accept up to 2.00" valves. Kit contains forged flat topped 3 9/16" bore pistons with coated piston skirts, S&S 3-9/16" bore cylinders, MLS head gaskets, base gaskets, exhaust gaskets, assembly lube, and instructions.


  • 10.3:1 Flat Top Pistons
  • 11.2:1 5.5cc Domed Pistons
  • Available in silver powder coat or wrinkle black powder coat finish
  • Made in the USA
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Please review this product's fitment notes & exceptions prior to purchase: Add to Cart

This product is vehicle specific. Click here to select your vehicle to ensure fitment.

Fitment Notes & Exceptions
  • Can not run stock 883 cylinder heads with this kit.
  • S&S does not recommend boring 2004 and later 883cc cylinders from 3" to 3-9/16" bore to increase engine displacement to 1250cc due to changes in factory cylinder and liner.
  • The cylinder fin profile does not perfectly match the fins on 2004 and later stock heads, but the difference is not considered to be objectionable.
  • See instructions for full details on installation.

This Product Fits:

Harley Davidson
Sportster Custom XL1200C 1996-2019
Sportster Custom XL883C 1998-2009
Sportster Deluxe XLH883DLX 1989, 1990, 1991, 1992
Sportster Forty-Eight Special XL1200XS 2018, 2019
Sportster Forty-Eight XL1200X 2010-2022
Sportster Hugger XLH883HUG 1988-2003
Sportster Iron XL1200NS 2018, 2019, 2020, 2021
Sportster Iron XL883N 2009-2022
Sportster Low/SuperLow XL883L 2005-2019
Sportster Low XL1200L 2006-2011
Sportster Nightster XL1200N 2007-2012
Sportster Roadster XL1200CX 2016, 2017, 2018, 2019, 2020
Sportster Roadster XL1200R 2004, 2005, 2006, 2007, 2008
Sportster Roadster XL883R 2002-2012
Sportster Seventy-Two XL1200V 2012, 2013, 2014, 2015, 2016
Sportster Sport XL1200S 1996-2003
Sportster SuperLow XL1200T 2014, 2015, 2016, 2017
Sportster XL883 2004-2009
Sportster XLH1100 1986, 1987, 1988
Sportster XLH1200 1988-2003
Sportster XLH883 1986-2003
Product Style Item # Store SKU Manufacturer Product # Availability
Product Style Black / 10.3:1 Compression Ratio Item # 1181564 Store SKU Manufacturer Product # 910-0691 Availability Available: Ships in 1-2 business days
Product Style 10.3:1 Compression Ratio / Silver Item # 1181565 Store SKU Manufacturer Product # 910-0689 Availability Available: Ships in 1-2 business days
Product Style Black / 11.2:1 Compression Ratio Item # 1181566 Store SKU Manufacturer Product # 910-0692 Availability Available: Ships in 1-2 business days
Product Style Silver / 11.2:1 Compression Ratio Item # 1181567 Store SKU Manufacturer Product # 910-0690 Availability Available: Ships in 1-2 business days
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