883 to 1200 quick question

[Guest]

thanks for that, it makes sense written out like that........had to ask,.... now back to me Shovels !!

[thecarfarmer]

The 883 heads used on the 1200 bore with flat top pistons will jump the compression up around 12:1 ......
With pump gas being 91 octane falls short for a street bike, a dish piston (Or modified the combustion chamber) would get the numbers down to where as pump gas will keep detonation from killing the motor...

Valve size:
Here's where it gets a bit problematic ... The swallow chambers of the 883 heads requires longer stems than what the 1200 valves have going on, in turn kinda limits high lifts cam profiles. *snip*

Another issue to be cognizant of when you get greedy for more power is that the 883 - length valves get close to each other during overlap with big cams.

My .02: if you want to make power, the best bet is heads with some cleanup & a high quality valve job. NHRS, Hammer, Baisley, Jesse 'Dragstews', are among the good shops. A set of cylinders that have been honed with torque plates are another critical part. Raising the compression (maybe not to 12:1) is a major help with performance when upgrading the cams

Buying a 1200/1250/1275 conversion kit can accomplish all of the above.

Once you go down that road, the engine doesn't know or care whether it started as an 883 or 1200.

Also, I ended up putting a larger rear sprocket on my bike (883 w/ N4 cams) so it'd rev higher. But I rarely went over 50-100 miles away from home

[Dougtheinternetannoyance123]

Uhhh, a bit of misinformation? All due respect but there is multiple ways of going about this from of course just buying a 1200 to begin with, But many people recomend that the 883 is the best bang for the buck and then follow 1-2-3-4 stage tuning over the HD tax.
Depends on what you want to end up with.
But a ton of build articles along with dyno print outs, parts used and different combinations on the XL forum.
Some go with the monster 1250 conversions too..
But some sound economics of using the special conversion kits, and still using the 883 heads, Its not the top HP combo but its cheap and adds a ton of power.
I have multiple Buells myself,, Tubers and XB so big bias to those, but you can affordably build a nice 883 that will run rings around most big twins and with a few tweaks is more cost effective than a 1200.

The S&S Hooligan kits are nice (And a site sponsor here) Is Zippers still around? They used to be popular and heavily promoted in the Sportster performance book.

But this is typical and cheap!!!! ,,See: http://www.nrhsperformance.com/ekit8831200.shtml

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.


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:

Or more:

NRHS 1250 PACKAGE WITH MATCHING CAMSHAFTS

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


Description
Black w/Highlighted Fins
Black
Silver
NRHS 1250cc package:
3.563" bore iron lined aluminum cylinders
CP 10.5:1 pistons, pins, clips, rings
Andrews N4 Camshafts
Cometic Top end gasket kit
Ring gapping
004-NAIL3563XL883PKG-BH
$950.00
Make payments with PayPal - it's fast, free and secure!

004-NAIL3563XL883PKG-B
$950.00
Make payments with PayPal - it's fast, free and secure!

004-NAIL3563XL883PKG-S

[Dougtheinternetannoyance123]

This makes a compelling case for a lot for a little, and a Lot more $$$$ for just a little.