I am thinking of trying to get a little more power out of my 2003 Sportster 1200.

I forget what the stock HP for my bike was something like 50 HP's? With the pipes, jetting and aircleaner, I figure I am somewhere around my 60 HP's??

Now the Buell, with the same base motor, puts out 103 Hp's. I want to look into the conversions to put the Buell heads and cams, and maybe jugs, in the HD 1200 motor. I don't want to go crazy with NOS or anything like that, but I would like to get the XLC up to near 100 HP's, if possible...with out spending a million dollars.

I did a search on here to see if this topic came up, but found mostly 883 to 1200 conversions. For those that have the knowledge, here are my quesions:

1. Is there a kit on the market to do this now?
2. How much does it cost?
3. How many parts of the motor will I have to change?
4. What are the true HP numbers for the finished conversion?

Thanks for any help in advance.

I have Buell Thunderstom heads, Buell cyclinders and pistons on my bike. Total cost was around a grand. Total HP about 103. RWHP about 90.

(1@) 16797-98Y - HIGH FLOW HEAD, FRONT, BLK, THUNDERSTORM
(1@) 16827-98YB - CYLINDER HEAD, RR, BLACK, HI-FLOW
(2@) 16871-99Y CYLINDER, PTD BLACK
(1@) 17026-91D GASKET KIT, ENGINE
(1@) 17056-01 KIT, HEAD GASKETS (Screaming Eagle)
(2@) 22676-98Y PISTON & RING KIT - STD (Stock Bore)
If you want to go with a .30 bore in the cylinders order:
(2@) 22681-98Y - PISTON & RING KIT - .030 O.S.D
(1@) 32978-98A KIT, IGNITION MODULE 6800 RPM (Screaming Eagle)
(1@) 25649-01 SE PERFORMANCE XL CAM SET (Screaming Eagle)

I bought all these parts online at Chicago Harley. They will give you 20% off your purchase.

Thunderheader exhaust system. $500.00

I have Buell Thunderstom heads, Buell cyclinders and pistons on my bike. Total cost was around a grand. Total HP about 103. RWHP about 90.

(1@) 16797-98Y - HIGH FLOW HEAD, FRONT, BLK, THUNDERSTORM
(1@) 16827-98YB - CYLINDER HEAD, RR, BLACK, HI-FLOW
(2@) 16871-99Y CYLINDER, PTD BLACK
(1@) 17026-91D GASKET KIT, ENGINE
(1@) 17056-01 KIT, HEAD GASKETS (Screaming Eagle)
(2@) 22676-98Y PISTON & RING KIT - STD (Stock Bore)
If you want to go with a .30 bore in the cylinders order:
(2@) 22681-98Y - PISTON & RING KIT - .030 O.S.D
(1@) 32978-98A KIT, IGNITION MODULE 6800 RPM (Screaming Eagle)
(1@) 25649-01 SE PERFORMANCE XL CAM SET (Screaming Eagle)

I bought all these parts online at Chicago Harley. They will give you 20% off your purchase.

Thunderheader exhaust system. $500.00

Thanks Ray..that is exactly what I was looking for. If you don't mind my asking, about how much $$$ was everything together when it was done??
Did you do the work yourself, or have a shop/dealer do it??

Thanks again.

The new XB heads (silver) or XL1200R/C heads (black w/highlighted fins) are a better head than the Thunderstorms. Same valve sizes but it's a better port and chamber. Also the chamber is made to work with flat tops like all Sportster have, so you don't need the Thunderstorm pistons.

They're not difficult to fit to 91-03 Sportsters.

HD doesn't offer them as an assembled unit. However, we offer them completely assembled with the deck trued and with high flow stainless valves instead of the factory valves for the same price as all of the components list for. Moree info here:

http://www.nrhsperformance.com/partsoemheads.shtml

Thanks Ray..that is exactly what I was looking for. If you don't mind my asking, about how much $$$ was everything together when it was done??
Did you do the work yourself, or have a shop/dealer do it??

Thanks again.I did the work myself. Total cost was about $1700.00 w/misc. gaskets and the Thunderheader exhaust w/shields.

Around May or June I'll send the heads off to Nallin's for their stage 3 head work. I think that will be another grand or close to it.

G'day Doug

Those Buell numbers are taken at the crank .... Sporty numbers are at the rear wheel.

If ya want somethin to run hard then talk to Aaron (NRHS) about a complete package.....

They've got the runs on the board and can give you the numbers you want first time...

Saves the guess work as they've already done the development

http://www.nrhsperformance.com/pictures/tstormchamber.jpg

This is a Thunderstorm chamber. It's 67cc with a 15 degree squish band cast into it. A flat top at 67cc gives about 9:1 compression. Buell paired this head with a 15 degree domed piston though and bumped it up to 10:1.

I like angled squish bands, they direct the fuel being squeezd out of the squish bands more directly at the flame front. But the way it's done in the t-storm, it's really rough. Since it's cast in, it's uneven. Typically from the factory the clearance is .050 or more, and that makes the squish band largely ineffective anyway.

We can machine them nice and even, but there's a huge overhang around the perimeter. So to machine it, we typically have to take .035 to .045 off the deck, sometimes more:

http://www.nrhsperformance.com/pictures/stage3tstormheads.jpg

Here's an example after machining. This is much better, we can get a nice, even, consistent squish clearance. But cutting the deck this much has some side effects, like less valve to piston clearance as well as potentially forcing the customer into short or adjustable pushrods. It also typically makes the chamber too small, forcing us to open it up in other areas.

Also notice how there's not a whole lot of surface area. This squish band is effective up to about a .125 tall dome, anything higher than that and the dome goes past the squish band.

Which brings me to why I like the XB/04XL chamber so much:

http://www.nrhsperformance.com/images/xbhead.jpg

As delivered, they have flat squish bands with a 62cc chamber. This lets you toss them on over flat tops and have a squish band with lots of area and 10:1 compression. Not a bad way to do it.

If you want to angle it ...

http://www.nrhsperformance.com/pictures/xbstage3heads.jpg

... it's not a problem, you've got lots of material to work with. You can make the squish band as big or small as you want, make it match the piston you're using exactly, do relief cuts with the rest of the material to help overlap flow if you want. You can do all this without excessive deck milling and all the problems that come with it.

The stock valves are the same sizes as the Thunderstorms, 1.810" intake and 1.575" exhaust. The springs and guides can support up to .550 lift safely, though, versus .500 for the Thunderstorms. The ports are actually a little better than the Thunderstorms.

The Thunderstorms were a major step forward from the Lightning/Screaming Eagle heads, but the new XB/04 XL1200 heads are even better IMO.

Wow aswracing...thanks for all of the detailed information. I appreciate it.

aswracing thanks for sharing and I will add that I'm happy you have become a supporting vendor.

It's folks like you and Stevo who provide the meat and potatoes information that a lot of us folks like and need and I for one find you folks extremely helpful, thoughtful, and an invaluable resource for good and accurate information.

Now my question, what would you recommend for someone that already has the Thunderstorm heads? I was thinking of doing a stage 3 on them soon but now you have me wondering if maybe I should hold off and get a set of the XB's.

The Thunderstorm is a good head and we've made a lot of power with them (over 120hp on race engines at 1250cc). We did a set just last week that flowed 179cfm for example (@10"). If you're going Stage 3, I dunno, it's hard to justify the extra expense of replacing your heads. But then again, if you can sell your old heads on E-bay for a reasonable price, it might be worth it.