Hammer Performance 883 to 1250 XL Sportster 1986-Present Conversion Kit
Hammer Performance 883 to 1250 XL Sportster 1986-Present Conversion Kit
Hammer Performance 883 to 1250 XL Sportster 1986-Present Conversion Kit
Hammer Performance

Hammer Performance 883 to 1250 XL Sportster 1986-Present Conversion Kit

Regular price £624.99 £0.00

BOLT-ON 1250 Kits from HAMMER PERFORMANCE

For 1986-present 883 & 1200cc Sportsters and Buell - From £624.99!

The legendary HAMMER 1250 Kit is a bolt-on that can be installed in an afternoon without case boring and without removing your engine from the frame.

Each kit comes standard with the best components on the market:

  • Sledge Hammer 3-9/16 Bore Iron Lined Aluminium Cylinders
  • Sledge Hammer 3-9/16 Bore Forged Pistons
  • Lightweight Tool Steel Wrist Pins
  • Circlips
  • Premium Quality Moly Faced Rings

What Makes HAMMER 1250 Kits the Best?
Several things! Let's start with the Sledge Hammer 1250 cylinders, which feature an extra heavy duty iron liner and aluminium fin construction:
Why a thick liner? A thick liner promotes a straight, round bore under the heat and stress of a running motor. This provides superb ring seal. The iron liner material is also rock hard for a long, trouble free life, and the aluminium fins promote excellent heat dissipation. Iron lined aluminium is the proven best cylinder construction for street ridden bikes, without the streaking issues of nikasil or the heat and weight issues of full cast iron construction, and we believe the HAMMER 1250 cylinder is the best iron lined 1250 cylinder on the market. There are thousands and thousands of these cylinders in service, in bikes all over the world, making great power and performing flawlessly. You cannot buy a finer cylinder!

In addition to the superior construction, these are the ONLY 1250 cylinders available in the 2004+ big fin style! See the picture above. Other companies ask you to put the 1986-2003 small fin cylinders onto your 2004+ bike. And yes, they can be made to fit the late model bikes by grinding on the lowest fin. But that's a hack! And on top of that, you'll reduce the cooling capacity of your motor. Big fins came out in 2004 for a reason; cylinder pressures on the 1200 models were raised dramatically starting in 2004. Big fins were part of a coordinated plan to manage the additional heat. Other things that were done were MAP based ignition and oil jets to cool the undersides of the piston domes. Head fin sizes were changed at the same time, and using small fin cylinders causes an appearance mismatch. It's just an all around bad plan. Don't go backwards in cooling capacity or appearance - use SLEDGE HAMMER CYLINDERS from HAMMER PERFORMANCE!

And finally, if you've got the black highlighted look on your bike, there's yet another compelling reason to choose SLEDGE HAMMER cylinders:

These kits give a power increase over the entire rpm range. Unlike most mods that rob from one area to give to another, with a 1250 kit you get an across the board gain. Take a look at these actual results:

Here's what a 1250 brings to a late model EFI 883
This motor has stock EFI 883 heads and W cams
In blue is a 1250 kit with reverse dome conversion pistons and stage 1 mods (exhaust, air cleaner, tuner)
In green is the stock XL883

Click here for more information on converting your 883

Here's what a 1250 kit brings to a late model EFI 1200
This motor has stock EFI 1200 heads, stock W cams, and stage 1 mods (air cleaner, exhaust, tuner)
In blue is a flat top 1250 kit
In red is the stock 1200 cylinders and pistons

 

The best 1250 pistons on the market! Complementing these great cylinders is a set of our exclusive forged Sledge Hammer pistons. These pistons feature extra large valve pockets for those radical cams, anti-detonation grooves, dual wrist pin oilers, expansion grooves for superior ring seal, and for maximum strength with minimum weight. You cannot find a finer piston for your HD or Buell.

 

Tech Tip: Are you converting an 883? Be sure to read the tech article on conversions for lots of good information to make your project a success!

1250 & 1275 Kit Options
Depending on the year of your bike, other components are necessary for a successful 1250 or 1275 conversion. Specifically:

  • All 86-03 models should get a new ignition system that provides a timing curve appropriate for the 1250 kit. However, since this year range has adjustable ignition timing, the new ignition is not strictly necessary. Read this FAQ for a more detailed explanation
  • All 04-06 models need a new ignition system, to provide a timing curve that's appropriate for the 1250/1275 kit. This year range has no other method for making a timing adjustment and therefore the module is mandatory.
  • All carbureted models (86-06) need a couple of carb jets, to properly adjust the fuel delivery for the larger displacement
  • All injected models (07-Up) need a flash type tuner to adjust both timing and fuelling
  • All 04+ 883 models need a new clutch spring at a minimum, however an extra plate clutch pack is recommended to eliminate a common point of failure in the stock clutch
  • All Sportster models need a colder set of spark plugs than the factory stock 6R12's, to prevent detonation with the higher cylinder pressure that comes with the engine kit. We recommend and offer the HD 10R12X Gold plugs in the table below. These were standard equipment in XR1200 models, and they're a high quality plug with a special tip design that resists fouling and gives a long life.

Fancy trying to fit it yourself? Check out this great install video below. Lets save you some more cash!


 

Tech Tip: Are you converting an 883? Be sure to read the tech article on conversions for lots of good information to make your project a success!

 

*SHIPPING CAN TAKE 2-3 WEEKS APPROXIMATELY DEPENDING ON WHAT WE HAVE IN STOCK AS OUR SUPPLIER MAKES THESE TO ORDER*


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