883 to 1250cc Conversion Kits


NOTE: These kits work with stock 883 cylinder heads. No modification required.




Converting your 883 Sportster to a 1200 or better yet a 1250 is one of the best performance investments you can make. But to do it successfully, you need high quality parts and services. NRHS has what you need!


Street Dominator 883 to 1250 Conversion Package - From $599.95


***This kit works on ALL 1986 and up XL's to include 2009 and newer models.



The famous NRHS 1250 kit is now available in a conversion package! This kit takes your 883 to the largest displacement that will fit into the stock cases without the hassle and expense of case boring. These kits are available in your choice of colors: silver, black or black-highlighted. The iron-lined aluminum construction offers excellent heat dissipation together with the structural integrity and ring seal of a thick ductile iron liner that wears much less than the factory cylinder. Coupled with premium NRHS Hurricane Forged pistons, Total Seal rings, and Cometic gaskets, we feel this is the ultimate kit for your Sportster!


These kits work on all EVO Sportsters 1986 and up to include the newest fuel injected models.


Note:  all of our kits use the 2003 and older style cylinders. They bolt up just like the newer cylinders but the fins are slightly smaller. In our experience this does not cause any extra heat and most folks cannot tell the difference when installed. Pictured below is a NRHS 1250 kit with 2007 XL 1200 heads.



***Note: If you have a 2004 and newer XL, you will need to either upgrade to an adjustable ignition module or ECM tuner to compensate for the added compression of this kit.

Click here for more details about ignitions.




This kit includes:

   - One set of premium Hurricane reverse-dome conversion pistons in 3-9/16 bore

      these provide a 10:1 compression ratio with your stock 883 cylinder heads

   - One set of new Axtell cast-iron cylinders, or NRHS iron lined aluminum cylinders

   - Rings, pins, locks, and circlips

   - Cometic EST head/base gasket set


Actual results obtained in the NRHS shop from our 2004 Sportster XL 883:



This provides an idea of what to expect from the NRHS/Axtell Street Dominator conversion kit when used with your 883 heads and supporting components*. Only the head preparation level was changed between the top three pulls, all other components remained the same. The original stock 883 result is also shown for reference, in purple. That's right, with the bolt-on 1250 kit and these supporting parts, you can more than DOUBLE the power of your stock 883. You won't believe how much more fun your bike will be!


For even more power, swap your 883 heads out for a set of NRHS prepared Thunderstorm or XB Heads. Many NRHS customers have made over 100 rear wheel horsepower using these higher flowing heads with the 1250 kit. The bikes are smooth, strong, reliability is unaffected, and longevity is actually improved.


* - The bike that generated this dyno sheet is also equipped with a HurricaneFlow Air Cleaner, Mikuni HSR42 carburetor, SE .536 cams, Supertrapp exhaust system, and Daytona Twin-Tec ignition.



Ordering Information


NRHS Iron Lined Aluminum Cylinder Kits



Black Highlighted



Street Dominator 883 to 1250 Conversion Package

Iron Lined Aluminum Cylinders

Fits 86 and up 883 Sportster








Options to Make These Kits Even Better!


If your bike is over 2 years old or has more than 4,000 miles, you should consider upgrading to a full Cometic top end gasket kit. These kits include all rocker box, head, base, pushrod, intake and exhaust gaskets.


If you would like NRHS to gap your rings and pre-install your assembled pistons into pre-lubed cylinders you can also order that below.



Ordering Information 





Part Number



Top End Gasket Kit Upgrade

1986-1990 Four Speed XL's



Top End Gasket Kit Upgrade

1991-2003 XL's



Top End Gasket Kit Upgrade

2004-2006 XL's



Top End Gasket Kit Upgrade

2007 and up



Ring gap and pre-install pistons

***Regular price $50, Special price $1.00***







Want even more power? NRHS has packages that include both the NRHS 1250 kit, gasket kit and matching camshafts that are proven on the dyno and on the street to work exceptionally well together. Buying a matched package takes the guesswork and error out of your project!


Note: This is for use with all 1986 and up 883 cylinder heads




Black w/Highlighted Fins



NRHS 1250cc package:

3.563" bore iron lined aluminum cylinders

CP 10:1 pistons, pins, clips, rings

Andrews N4 Camshafts

Cometic Top end gasket kit

Ring gapping









Not seeing what you want? Give us a call at 573-759-2834! We have tremendous experience at hot-rodding and racing XL's and we'll be happy to put together a package that works for you.