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====== Pics and Information on Evo Sportster Heads ====== | ====== Pics and Information on Evo Sportster Heads ====== | ||
+ | Article originally written by aswracing of the XLFORUM with further commentary by NRHS Sales of the XLFORUM and extended with further pics and information. ((https://www.xlforum.net/forum/vendors/nrhs-high-performance/161314-sportster-heads-general-information?highlight=883r+heads#post4722973)) \\ | ||
+ | Some of this information is now outdated as some of these heads have been obsoleted. \\ | ||
+ | However, the information itself is very informative regarding the changes and specs on the different stock heads. \\ | ||
+ | ====== Evo Sportster Heads ====== | ||
+ | |||
+ | ===== General Information ===== | ||
+ | There are 4 generations of Evo Sportster heads: | ||
+ | * 1986-1990 (4 speeds) | ||
+ | * 1991-2003 (5 speeds) | ||
+ | * 2004-present (rubber mounts) | ||
+ | * 2007-up (fuel injected) | ||
+ | |||
+ | ===== Casting Numbers ===== | ||
+ | |||
+ | | 1998 XL1200S Head Castings on Top ((photos by Hippysmack)) || | ||
+ | |{{:techtalk:evo:engmech:heads_-_1998_1200s_pic4_by_hippysmack.jpg?direct&300|}}|{{:techtalk:evo:engmech:heads_-_1998_1200s_pic3_by_hippysmack.jpg?direct&300|}}| | ||
+ | |||
+ | ===== Interchangeability ===== | ||
+ | Within a given generation, the heads are mechanically interchangeable between the different models, i.e. all bolt holes line up and no needed features are missing. \\ | ||
+ | Valve geometry is the same: 27° intake & 31° exhaust for a 58° included angle and the location of the valve tips is the same. \\ | ||
+ | |||
+ | The rocker box bolt pattern has not changed across any of these generations. A 1986 lower rocker box will bolt right up to a 2006 head and vice-versa. \\ | ||
+ | |||
+ | **Crankcase Breathing**: \\ | ||
+ | The only thing you need to be aware of is that the crankcase breathing arrangement has changed at each of the generations below. \\ | ||
+ | * 4-speed models provided no facility in the head for a crankcase breather (the blind hole in each head is used to mount the carb). | ||
+ | * 5-speed models incorporated crankcase breathers into the carb mount bolts in the heads (open hole through head). \\ They also use a different middle rocker box that has a check valve incorporated (aka "umbrella" valve). | ||
+ | * Rubber mount models use an air/oil separator & check valve unit bolted into the lower rocker box. \\ (and do away with the middle rocker box, using a different top cover) | ||
+ | |||
+ | **1991-2003 heads have been successfully fitted to 1986-1990 models**. \\ | ||
+ | The major difference you need to be aware of is that the spacing between the pushrod holes is different between a 4 speed and a 5 speed models. \\ | ||
+ | This is because the cam box geometry is different and the pushrods are at a different angle. \\ | ||
+ | So pay attention to the potential for pushrod rub where they pass through the heads into the rocker box. \\ | ||
+ | |||
+ | **2004-2006 heads have been successfully fitted to 1991-2003 models**. \\ | ||
+ | The new heads have the right front bolt hole relocated inboard 1/4", and also use 7/16" fasteners as opposed to the 3/8 fasteners used on the 1991-2003 models. \\ | ||
+ | You can either modify your existing front mount, or more recently a new mount has become available that solves this issue. \\ | ||
+ | Also, be aware that the 2004-2006 heads have larger fins and will overhang 1991-2003 cylinders somewhat, most noticeable on the left side. \\ | ||
+ | You can use your stock 1991-2003 rocker boxes or use the 04-up rocker boxes, either will work fine. \\ | ||
+ | |||
+ | **The 2007 and up fuel injected heads will technically fit older models but they are 1/8 wider in the intake manifold area**. \\ | ||
+ | So some folks report sealing issues when using on older bikes. \\ | ||
+ | They also have a different intake bolt pattern so you must use 2007 and up manifold flanges when using these heads. \\ | ||
+ | |||
+ | Anytime you're putting a different set of heads on your bike, you need to be aware of the chamber size & shape. \\ | ||
+ | And also how it relates to the piston you're using (to make sure they're mechanically compatible and will give the desired compression ratio). \\ | ||
+ | |||
+ | ====== 883 XL Specific Information ====== | ||
+ | 883 heads (ALL GENERATIONS) have a small, 49cc chamber that's approximately 3" in diameter to match the 3" bore of the 883. \\ | ||
+ | The chamber is also more shallow than the chamber in any other Sportster head. \\ | ||
+ | Valvetrain geometry is the same as the other heads except that small 1.580" intake & 1.350" exhaust valves are used. \\ | ||
+ | And the valves are longer to work with the more shallow and smaller diameter chamber. \\ | ||
+ | |||
+ | In stock configuration, these are the worst ports of any XL head, primarily due to the way the bowl area squeezes down to the small diameter valve. \\ | ||
+ | This arrangement causes a lot of turbulence. \\ | ||
+ | The heads respond well to a good porting and seat blending job, particularly when used with a larger valve that better matches the bowl size. \\ | ||
+ | The seats can accomodate the standard XLH1200 valve sizes (1.715 intake/1.480 exhaust) and special longer "conversion valves" are available to do this upgrade. \\ | ||
+ | You can have larger 1.760" Intake and 1.530" exhaust valves with stage 2 headwork (with the right machine shop and parts kit). | ||
+ | |||
+ | When used in an 883 to 1200 conversion, reverse dome (dish) conversion pistons are available to give a workable compression ratio. \\ | ||
+ | Alternatively, the chamber can be relieved and the heads used with flat top pistons. \\ | ||
+ | |||
+ | These heads have an advantage over the XLH1200 hemi chamber head. \\ | ||
+ | The 3" diameter chamber provides a "squish band" around it's perimeter when placed over the larger 1200 bore. \\ | ||
+ | The squish band results in more turbulence and a more efficient chamber. \\ | ||
+ | However, the longer valves in these heads are also a disadvantage in that piston to valve contact issues are much more likely. \\ | ||
+ | Be concerned about this if the cams you're using have a high TDC lift figure on one or both valves. \\ | ||
+ | |||
+ | Most sets of 883 heads you come across will be silver in color. 883R and Iron models have black 883 heads. \\ | ||
+ | All are easily identified by the "883" script cast into them adjacent to the chamber. \\ | ||
+ | |||
+ | ====== 1100 and 1200 XL Specific Information ====== | ||
+ | **1986-1987 XLH1100 HEADS**: \\ | ||
+ | These heads are very rare and very desirable. \\ | ||
+ | They came stock with large 1.840" Intake and 1.610" exhaust valves and a 62cc chamber which gave increased compression. | ||
+ | |||
+ | **1988-2003 XLH1200 HEADS**: \\ | ||
+ | These heads have a 67cc hemispherical chamber, i.e. it's a round bowl with no squish band. \\ | ||
+ | Hemi chambers provide maximum valve unshrouding but also tend to have poorer chamber turbulence. \\ | ||
+ | The 67cc volume gives about 9:1 compression with flat tops at 1200cc. Domed pistons are readily available to raise this number up to 10:1 or higher. \\ | ||
+ | The pistons designed for this chamber have a radiused edge on the domes to fit well inside the hemi chamber shape. \\ | ||
+ | But the irregularity of the chamber (which is just a casting) makes it impossible to achieve a good squish band. \\ | ||
+ | |||
+ | Valve sizes are 1.715" intake and 1.480" exhaust. The stock seats can support only slightly larger sizes. \\ | ||
+ | (we fit them with 1.760" intakes and 1.530" exhausts when doing a Stage 2 job. For Stage 3 we change the seats) \\ | ||
+ | |||
+ | The ports on these heads are not particularly good, they have something of a squared off bowl and a low floor. \\ | ||
+ | In other words, these are areas where they need more material. These heads are all black with polished fins. \\ | ||
+ | |||
+ | **2004-up XL1200 Heads (all models)**: \\ | ||
+ | These are the best heads the factory has ever put on a Sportster. \\ | ||
+ | They are virtually identical to the Buell XB heads with 1.810" Intake and 1.575" exhaust valves with 7mm stems. \\ | ||
+ | They have 62cc bathtub shaped combustion chambers. They are either all black or black with highlighted fins. \\ | ||
+ | |||
+ | | 1998 XL1200S Heads ((photo by Hippysmack)) ||| | ||
+ | |{{:techtalk:evo:engmech:heads_-_1998_1200s_pic1_by_hippysmack.jpg?direct&300|}}|{{:techtalk:evo:engmech:heads_-_1998_1200s_pic2_by_hippysmack.jpg?direct&300|}}|{{:techtalk:evo:engmech:heads_-_1998_1200s_pic5_by_hippysmack.jpg?direct&300|}}| | ||
+ | |||
+ | ====== Buell Heads ====== | ||
+ | |||
+ | ===== General Information ===== | ||
+ | There are 2 generations of Buell heads: | ||
+ | * 1995-2002 (tube frame models, aka "tubers") | ||
+ | * 2003-present (XB models) (last edited in 2014) | ||
+ | |||
+ | **1995-2002 Buell heads can be considered the same generation as 1991-2003 Sportster heads**. \\ | ||
+ | The rocker box and head breather arrangements are identical, as are the fin sizes. \\ | ||
+ | The front mount holes have the same spacing as the 1991-2003 Sportster heads but use 7/16" NC fasteners. \\ | ||
+ | (exception: 1995-1996 S2 models use a 3/8" fastener on one side and a 7/16" fastener on the other). \\ | ||
+ | |||
+ | **2003-present Buell heads can be considered the same generation as 2004-present Sportster heads**. \\ | ||
+ | (in that they use large fins and 7/16" front mount fasteners with the right front mount hole moved inboard 1/4"). \\ | ||
+ | The main difference is that the XB head does not provide head breather/carb mount bolt holes. \\ | ||
+ | The bosses are cast in, however, and the holes can be drilled and tapped. \\ | ||
+ | Buell XB models don't need these bolt holes due to the downdraft fuel injection system they come with. \\ | ||
+ | Crankcase breathing is provided on stock XB models through the tops of the rocker box covers. \\ | ||
+ | |||
+ | ====== Buell Specific Information ====== | ||
+ | **1995-1996 BUELL S2 HEADS**: \\ | ||
+ | These heads are identical to the 1988-2003 XLH1200 heads in all respects except that one of the front mount bolt holes is 7/16" NC instead of 3/8" NC. \\ | ||
+ | So don't be fooled; not all "Buell Heads" are higher performance than Sportster heads. \\ | ||
+ | ** | ||
+ | 1996-2003 LIGHTNING HEADS**: \\ | ||
+ | This is a head that came out in 1996 on the Buell S1 Lightning model, as well as the 1200S Sportster Sport model. \\ | ||
+ | The 1200S version is black with polished fins and has dual plugs, the second plug being accessible through the hole in the top of the rocker box. \\ | ||
+ | The Buell S1 version is silver and has a single spark plug. Versions of this head were also sold in the Screaming Eagle catalog. \\ | ||
+ | Early versions were silver and carried the "Lightning" script above the pushrod area. A version was sold in black polished with no script. \\ | ||
+ | And finally, a black polished version was sold with the "Screamin Eagle" script and dual plugs. Also, the Buell Blast comes with a version of this head. \\ | ||
+ | |||
+ | The valve sizes are 1.715" intake and 1.480" exhaust (identical to the 1988-2003 XLH1200 head. \\ | ||
+ | The same seats are used so Stage 2 Lightning heads get 1.760" intakes and 1.530" exhausts. \\ | ||
+ | The ports are also identical to the 1988-2003 XLH1200 head. \\ | ||
+ | Later SE versions were advertised as having 8% higher flow than stock XLH1200 heads. \\ | ||
+ | But as someone who's flow tested lots of them, I just haven't seen it. The range of numbers I get has been the same. \\ | ||
+ | |||
+ | The only place this head is different from the 1988-2003 XL head is in the chamber. \\ | ||
+ | Extra material was added, as well as a 10° squish shelf, bringing the volume down to about 62cc. \\ | ||
+ | This gives around 10:1 when paired with flat top pistons. The squish band though does nothing with a flat top. \\ | ||
+ | So the performance increase from this head comes entirely from an extra point in compression ratio. \\ | ||
+ | |||
+ | This extra material in the chamber somewhat shrouds the valves, however, hurting low lift flow. \\ | ||
+ | It gets especially bad when oversize valves are fitted. \\ | ||
+ | When putting larger valves into Lightning heads, we always unshroud the chamber around the valve heavily to improve flow. \\ | ||
+ | This of course raises the chamber volume and requires us to deck the head significantly to get the volume back to 62cc. \\ | ||
+ | Often we'll end up re-cutting the squish band to 15° and just size the chamber out to 67cc instead, and then put the customer into a Thunderstorm type domed piston. \\ | ||
+ | We did, however, offer a 10° piston designed for the stock Lightning head that offers 10.5:1 compression at 62cc. \\ | ||
+ | |||
+ | **1998-2002 BUELL THUNDERSTORM HEADS**: \\ | ||
+ | This was the second generation high performance head to come out on Buells. \\ | ||
+ | It was introduced in 1998 on the S1W and S3/S3T (the S1 and the M2 retained the Lightning heads in 1998). \\ | ||
+ | In 1999, all models came with Thunderstorms and it remained that way through the 2002 model year. \\ | ||
+ | |||
+ | This head went back to the 67cc volume and instead used a domed piston to raise the compression ratio. The advantage to this is that it heavily unshrouded the valves. \\ | ||
+ | A 15° squish shelf was incorporated into the chamber and matched to a 15° dome angle on the piston. \\ | ||
+ | Also, valve sizes were increased to 1.810" intake and 1.575" exhaust. Ports were improved as well, particularly in the bowl. \\ | ||
+ | |||
+ | The squish shelf on a Thunderstorm head is still a casting, however, and as such it's not very accurate. \\ | ||
+ | There's a good sized overhang between the deck and the perimeter of the squish shelf, and core shift often makes the squish shelf uneven from side to side. \\ | ||
+ | So while it's nice to have a squish shelf and the turbulence it generates, it's effectiveness is limited unless you re-machine it. \\ | ||
+ | (which generally requires .030"-.040" to be removed from the deck) \\ | ||
+ | Still, this head performs substantially better than the Lightning or XLH1200 head. \\ | ||
+ | All Thunderstorm heads are black powder coated, without highlighted fins. \\ | ||
+ | |||
+ | **2003-up BUELL XB heads**: \\ | ||
+ | These heads are virtually identical to the 2004-up XL1200 heads but they do not have provisions for breathers as noted above. \\ | ||
+ | You can drill and tap for breathers though if needed. They come in either silver or all black color depending on model and year. \\ | ||