New OEM XL1200R and XB Heads Are Now Available Assembled from NRHS!

The new XB and 2004 XL1200R cylinder heads represent a major step forward in port design from previous OEM cylinder heads. When comparing stock to stock, our testing has shown these heads to be capable of 5-6 more horsepower than typical Thunderstorm heads! Complementing the much improved ports is a set of special lightweight large-diameter valves, single beehive style springs with extra travel, ultra-lightweight retainers & keepers, and an improved valve stem seal design. As a result of these improvements, the new XB/04XL heads are quickly becoming the OEM performance head of choice for XL's and Buells.

NRHS takes the hassle and expense out of using these new heads!

Until now, these heads were only available unassembled. NRHS now offers these heads professionally assembled with premium Hurricane valves for the same price as all of the individual stock components would cost you at your dealer!  We'll also drill and tap the breather holes for an extra $50 charge if desired on the XB heads. Other options include chamber work to accommodate angle dome pistons at your desired compression ratio, heavy duty valve train components, black powder coating, and Stage 1, 2, or 3 porting services. We also offer pushrods and pushrod cover kits as well as a Buell front engine mount to simplify the installation.

More Details

These heads feature 1.810" intake and 1.580" exhaust valves, the same size as Thunderstorm, but with 7mm stems for additional weight savings. A single beehive style valve spring controls each valve, further reducing weight at the critical top end of the spring which sees the most movement. The springs measure about 135lbs at 1.850" installed height when new. A new improved valve guide seal design is used as well. There is plenty of retainer-to-guide seal clearance and coil bind clearance to allow up to .550" of valve lift, a full .050" more than the earlier heads, opening up the possibility of using higher lift cams*. The heads use a bathtub style 62cc chamber with flat squish bands. At stock 1200 bore and stroke, this chamber provides approximately a 9.7:1 compression ratio with flat tops. The XB and 2004 XL1200R heads are identical in every way except the finish and the breather holes, which are already drilled and tapped on the 1200R heads but not on the XB heads (the XB heads already have the boss, however).

Professional Assembly Makes the Difference

During assembly, all new parts are used, and premium quality Hurricane stainless steel valves are installed (1.810 intake, 1.580" exhaust, 7mm stems). Stem protrusion is checked and adjusted as needed. Valve springs are fully tested for correct seat pressure and travel, and valve spring installed height is set. Valve-to-valve clearance is checked and we will advise if additional work is needed to correct (this is primarily a function of the cams you choose; cams with a lot of overlap may require clearancing work). Exhaust studs are installed. With XB heads, we'll drill and tap the breather holes if needed for an extra $50 charge. (04 XL heads already have these holes drilled and tapped). We can optionally shim the springs for additional seat pressure if needed for your cams*. All of that is done at no extra charge! For only a little bit more, we can cut the combustion chambers for an angled squish band and/or to achieve a desired compression ratio. And of course, if you'd like everything you can get out of these heads, we can fully port and flow them as well as fit ultra-high performance Hurricane valvetrain components. We've made as much as 125rwhp at 1250cc with Stage 3 ported XB heads, totally streetable!

* - Be careful about how aggressive of a cam lobe and how much spring pressure you put to OEM valves with 7mm stems. A big part of H-D's ability to get 7500rpm safely from these light duty components in the XB9 is the gentle profile of the stock XB cam lobes. We recommend converting to heavy duty Hurricane springs and Hurricane valves with 5/16" stems when using aggressive cam lobes.

Installation Issues

Stock XL rocker boxes bolt right up and the stock XL pushrod tubes work fine. Your stock pushrods may or may not work, because these heads are about .025" shorter than an XL or Thunderstorm head. By itself, this is generally not enough to necessitate custom pushrods. However, if you are shortening the stack further with additional milling to raise compression, milling of your cylinders, and/or thinner than stock gaskets, pushrod length may become a concern. The best way to determine if pushrod length is an issue is to measure the amount of lifter plunger preload you're getting, ideally the plunger should be centered in it's travel when the valves are closed (stock lifters have .200" of travel). We recommend correcting the pushrod length if the plunger is more than .050" away from centered. Pushrod length can be corrected by using Hurricane pushrods, which are available in either fully adjustable or fixed length versions. When using adjustable pushrods, we highly recommend a set of collapsible pushrod covers to facilitate adjustment.

Note that the right (pushrod side) front mounting hole on these heads is moved inward 1/4" from previous Evolution XL heads. Modification of your engine mount may be required. For owners of Buell tube frame models, we offer a billet aluminum mount with the hole correctly located for these heads. Designed to be extra-strong, this mount is CNC machined from a solid chunk of 6061T6 aluminum. Extra material is placed in all stressed areas and all corners are radiused to eliminate stress risers. If you've already fitted XB heads and you'd like to swap out your modified mount for this unit, it's a 15 minute job because unlike competing products, the bolt can be inserted from the bottom. This is a super high-quality piece that will complement your Buell nicely.

 For 86-03 Sportster owners we now offer a steel mount that has the mounting hole correctly located.  It is zinc plated so it will require painting or call us about powder coating services available.

Ordering Information 

Note: For black or silver heads, specify whether or not you need breather holes drilled and tapped

           Black w/polished fins are only provided with drilled & tapped breather holes

*  Black XB/04XL heads are not provided by HD. NRHS uses a set of XB heads and powder coats them

    black, hence  the extra cost.

Options

For even more performance, check out our XL/Buell Head Porting Services

Stage 2 XB heads cut with a 15 degree angled squish band and chamber

relief work to give 10.5:1 compression with Thunderstorm type pistons.

The 15 degree angle provides the air with a more direct path into and out

of the cylinder as compared to the stock flat squish bands, thereby

improving cylinder fill, and also directs the fuel being squeezed out of the

squish band more directly at the flame front. This angle also maintains

good squish band area for a given dome height, which maximizes chamber

turbulence and minimizes detonation. We recommend the 15 degree angle

for most street applications with moderate dome heights and compression ratios.

The top of the line! These Stage 3 XL1200R heads have been cut

with a 30 degree angled squish band for special application

racing pistons. The extra-large 1.900" intake valves have been

heavily unshrouded for maximum flow, and the 30 degree angle

complements this nicely by reducing even further the shelf that

the air must go around to fill the cylinder. Since it reduces squish

area at a given dome height, this angle is best suited to higher

dome, higher compression  pistons as commonly found in racing

or very hot street applications.

All chamber work is done on a state-of-the-art CNC machine to

ensure quality and accuracy.