Hammer Performance - for All Your Harley Davidson XL Sportster and Big Twin Performance Needs
Hammer Performance Horizontal Bar

Dyno Room and Results for Harley Davidson and Buell Performance Products and Services from HAMMER PERFORMANCE

New Harley Davidson and Buell Performance Products from HAMMER PERFORMANCE

Garage Sale Products from HAMMER PERFORMANCE

Harley Davidson and Buell Performance Photo Gallery

Pictures of Harley Davidson and Buell Performance Cylinder Heads

Pictures of Custom Air Hammer Air Cleaners


Quick Links:

PLEASE NOTE: This article is a work in progress. Check back for updates.

Background Information

If you have an XL1200 Sportster and you're considering performance upgrades, this article is for you. If you instead have an 883 model, see our tech article on converting your 883 instead.

We've organized this article differently than the 883 article, for the simple reason that the approach you should take varies greatly depending on the year of your 1200. That's because between the 2003 and 2004 model years, XL1200 heads went from being the worst to the best heads available for a performance application. So you have to take a whole different approach depending on which generation of 1200 you have. And on top of that, the 1986-1987 heads are a different animal yet. By comparison, 883 heads have pretty much the same performance capability from 1986 to present. If you're interested in more of the details of 1200 heads and their differences across generations, read this tech article.

In the sections below, we'll go over the best approach with each generation of 1200. However, no matter which generation of 1200 you have, certain things remain constant:

  • Exhaust systems have a profound effect on a motor, especially when you use cams that add overlap - and if you're looking for performance from cams, overlap is critical. We've tested a bunch of exhaust systems and there's a massive difference from one to the next both in the power produced and how it's distributed in the rpm range. You can find our XL exhaust system dyno test results here. An excellent choice is the Patriot Defender (available direct from Patriot here). Although it technically only fits 04+ models, lots of people have successfully fitted the Defender to their 86-03 bikes, it requires only the fabrication of one bracket.

  • Your choice in Air Cleaner can make or break your result. The power of the motor is going to get defined by what holds it back, and it only takes one part that's not up to the job to negate all that great motor work and constrain your result. So make a smart choice here. Two things about your air cleaner choice are critical:
    1. You need to have enough filter element surface area to support the power level you're targeting
    2. You should avoid air cleaners that recycle the blow-by back into the intake tract. Blow-by is exhaust that went past the rings instead of out the exhaust port. It's hot, it's depleted of oxygen, and it's carrying oil mist and condensaton that it picked up on it's travels through your crankcase and into your air cleaner. It robs power, it contributes to detonation, and it causes excessive carbon build-up. Do your motor a huge favor and divert it to a catch can or breather filter.
    No surprise here, but we recommend the Air Hammer line of air cleaners. For up to about 105hp, the IMPACT model is a good choice. For 105-115hp, your choice should be the CRUSH model. For any maximum effort, 115+hp build, choose the SLEDGE model.

  • Proper fueling is critical. If your bike is carbureted (86-06), this means jets. For a CV40 carb (commonly used up to a little over 90hp), a good starting point is a 185 main, a 45 pilot, and 3 turns out on the idle mixture screw. On the higher power packages we recommend a Mikuni HSR42 or HSR45 carb. Start with a 165 main (HSR42) or 175 main (HSR45) and a 27.5 pilot jet. If your bike is injected (07+), fueling is controlled by the ECM and adjusted via your tuner device. We offer and recommend the Dynojet Powervision tuner for all EFI performance packages.

  • A proper spark timing curve is also critical, as is the raising of the factory rev limit. The things you'll be doing to your motor to pull more power out of it also tend to increase the speed of the burn in your combustion chamber. It's absolutely critical that you soften the timing curve and reduce the total timing to compensate. If you fail to do this, the motor will lose power, run hot, and there's a very real chance you'll scuff your pistons. Softening the curve and pulling back the final timing will be accomplished via either the EFI tuner (07+ models) or an aftermarket ignition module (86-06 models). Likewise, these devices let you raise your rev limit, which is also critical to making more power, as rpm is half the power equation. A single fire ignition is not critical. It's factory stock on 2004+ models and there's no reason to remove it, but we've converted many 86-03 models to single fire and tested it extensively and found very little benefit. It doesn't hurt anything, but don't expect a big return on your performance dollar, in most applications it will be very hard to even measure it.

  • Is a 1250 or 1275 kit worth it when you've already got a 1200? We get asked this question a LOT. Sure, it makes sense if you're starting with an 883, but on a 1200 it's only an extra 50-75cc, so why bother? And that's true, if you're looking at the peak power alone. Take a look at this chart for example:

    Sportster 1200 vs 1250 vs 1275 with no other changes

    This is an EFI 1200 and the only change between the three pulls is the displacement as indicated, and the bike was tuned up for each. All three motor sizes used flat top pistons.

    Notice what happened. The peak horsepower didn't go up all that much, just a couple hp at each step. But through the bottom and middle of the rpm range, there was a LOT of gain. That's no coincidence, by the way, that's exactly what happens when you make a motor bigger but keep the same level of breathing. Through the bottom and middle, things are happening slow and there's plenty of time to fill the cylinder and therefore the size of the motor has a pretty direct effect on how much torque (and thus power) it's putting out. But as you get into high rpm, there's not enough time to fill the cylinder anymore, and therefore the displacement increase does less for you. In other words, the motor becomes breathing constrained instead of displacement constrained.

    For many guys, the bottom end to mid range power is what they want anyway, so they go ahead and do a 1250 or 1275 kit and use their stock heads and cams. But what if you're going for a big top end number? Does the 1250/1275 kit still make sense?

    The answer is that in the case of the 1275 at least, absolutely. The reason is that if you're going to be making breathing improvements, you'll need new pistons anyway. Making the valves bigger and running more overlap in your cams and running late intake close timing all cause the compression to drop. You've got to have pistons with more dome to do those things. Well, if you need to change your pistons anyway, you're no longer looking at the cost of the 1275 kit, now you're looking at the additional cost of the 1275 kit as compared to boring and honing your stock cylinders and fitting new pistons. And that's a lot smaller number. Now the 1275 kit represents the cheapest power you can buy, that's the point where it makes sense.

  • If you get a 1250 or 1275 kit, get the right cylinders. There are basically two cylinder styles:

    Small Fin and Big Fin 1250 cylinders

    As you can see, there's a pretty dramatic difference in the fin sizes between an 86-03 and an 04+ cylinder. This affects both appearance and cooling performance. While small fin cylinders can be made to fit onto 04+ bikes, we really don't recommend it as it compromises cooling and won't look right under the big fin heads that all 04+ bikes came with. On the other hand, putting the big fin cylinders onto an 86-03 bike will enhance cooling. Make your own judgment about whether or not that's a worthwhile trade-off for the appearance issue of putting large fin cylinders under small fin heads. On the other hand, if you're updating your small fin heads to big fin versions, going with big fin cylinders to match and improve cooling at the same time is a no-brainer.

  • Appearance matters!. Many 1200's came from the factory with the black highlighted look, meaning the fins on the heads and cylinders are machined on the outer edge for appearance. Well, not only do some companies try to sell small fin 1250 cylinders into big fin applications (see above), but they also don't bother to properly machine the fins on their cylinders, they just hit them with a sander instead. All black highlighted HAMMER PERFORMANCE 1250 and 1275 cylinders receive CNC machined fin edges, big fin or small fin. Here, take a look at the difference between a competitor's sanded fin 1250 cylinder and a quality 1250 cylinder from HAMMER PERFORMANCE:

    Small Fin 1250 cylinder with sanded fin edges vs. Big Fin 1250 cylinder with machined fin edges

    Which would you rather have on your bike?

2004+ Models

In 2004, HD fitted the Buell XB style heads and "W" cams to all 1200's. All the XL's also got new big fin heads and cylinders as well as a MAP based crank trigger ignition system. Then in 2007, the bikes all got electronic fuel injection (EFI), which obsoleted both the carb and ignition module. But other than the fueling and spark control, the approach to hopping up these two generations is the same, so we've chosen to describe them both together.

Despite having the same cams and nearly identical heads, 07+ XL1200's (EFI) tend to make more power than 04-06 XL1200's (carbureted). There are a couple of reasons for this. For one, the throttle plate in the throttle body is a full 45mm, as compared to the 40mm CV carb found on the 04-06 models. For another, EFI makes more power because the cylinders can be tuned individually. Between these two items, you can expect 5-10% more power from any given configuration on an 07+ as compared to an 04-06.

The basic sequence to hopping up either version is as follows, in the order of importance:

  1. Address the fueling and spark advance as described in the Background Information section. For an 07+, our recommendation is a Powervision unit, optionally equipped with either the Target Tune (closed loop wide band) or Autotune Pro add-on. For applications targeting 105 to 120 horsepower, you should also have us perform our porting service on the stock throttle body and manifold assembly ($100). For applications targeting over 120hp, we recommend an HPI 51mm or 55mm throttle body ($790) along with the porting service ($100). See our tech article on throttle body testing for more information.

    For the 04-06 bikes, we recommend a Daytona Twin-Tec TC88A ignition module, and either a rejet of the stock carb (for applications under 90hp), or a Mikuni HSR series carb for higher power applications. Choose your Mikuni HSR based on your ultimate power goal: the HSR42 for up to about 105hp, the HSR45 for up to about 120hp, and the HSR48 for over 120hp. Also have us port your factory intake manifold for power levels up to 105hp ($60) or use a HAMMER Billet Intake Manifold for applications over 105hp.

  2. Choose a capable exhaust system and air cleaner as described in the Background Information section. The combination of a Patriot Defender exhaust and Air Hammer air cleaner is tough to beat.

  3. Change the cams. This is the next thing holding the motor back. The factory "W" cams are well optimized for bottom end and mid range power, but they really die on top. We have two cam grinds available that are bolt-in for a late model XL1200, meaning they'll work with the stock valvetrain components, heads, and pistons. Check out these charts for more information:

    Dyno chart sheet for HAMMER PERFORMANCE JackHammer 570 cams vs. stock W cams on a 2007 XL1200 Sportster Equipped with Cycle Shack slip-on mufflers

    The above chart shows what happened when we installed a set of JACKHAMMER 570 cams in a stage 1 2007 XL1200. The bike was equipped with a set of Cycle Shack slip-ons, an Air Hammer air cleaner, and it was tuned with a Powervision. Notice what happened. The 570's delivered a nice gain over a wide rpm range without losing any power anywhere. This is really good, because as mentioned, the stock W cams are optimized for bottom end and mid range. Most cam swaps on these late model 1200's will cost power on the left side of the chart to give power on the right side of the chart, so getting a gain without losing anything is progress. The 570 cams were designed with this goal specifically in mind.

    Now look at this chart:

    Dyno chart sheet for HAMMER PERFORMANCE JackHammer 570 cams vs. stock W cams on a 2007 XL1200 Sportster Equipped with a Patriot Defender exhaust system

    The above chart is the exact same comparison, except it was done with a Patriot Defender exhaust system in place instead of the Cycle Shack slip-ons. Look what happened, the gains from the cams got concentrated on the top side of the chart. Essentially we got twice as much gain over half as much range, with still no loss anywhere. So the moral of the story here is that the pipe has a lot to say about the magnitude and placement of the gains you can expect out of the cams; the two work together.

    One more chart on cams:

    Dyno chart sheet for HAMMER PERFORMANCE IMPACT 560 cams vs. stock W cams on a 2007 XL1200 Sportster Equipped with a Patriot Defender exhaust system

    In the above chart, we installed a set of IMPACT 560 cams into the bike. Notice what happened, we got a small loss over most of the rpm range, and in return we got a whopping 14hp gain on top! That's a massive gain from a cam swap, but when you look at the chart, you realize that you have to spin the motor up to see the gain, and you pay a price for it everywhere else. A big part of that is because these cams are really better suited to a 10.5:1 compression ratio, and the factory compression ratio at only 9.7:1 is on the low side. 9.7:1 is about perfect for the 570 cams however.

    HAMMER offers another set of cams that's suitable for a 2007 1200 as well, our CRUSH 600 cams. However, they do not work with stock heads, and they need even more compression to really work properly, so the CRUSH 600's are normally only used in conjunction with head work and domed pistons. This all gets back to proper matching of the heads and pistons and cams. If working with the stock heads and pistons, the JACKHAMMER 570 cams are the right choice for most people. Start changing the pistons and heads, however, and the story changes.

  4. Install a 1250 Kit. As described in the background information, this is more than just the extra 50cc of displacement. The truth is, to continue up the horsepower food chain, you're going to need more compression. Even the 560 cam swap as described above is suffering due to lack of compression. Since you're going to need new pistons anyway, the incremental cost of going 1250 versus fitting up new 1200 pistons makes the 5-7% more power of the 1250 kit some awfully cheap power.

    Here's what happened when we applied a 10.5:1 compression ratio 1250 kit to the previous chart with the 560 cams:

    Dyno chart sheet for HAMMER PERFORMANCE IMPACT 560 cams vs. stock W cams on a 2007 XL1200 Sportster Equipped with a Patriot Defender exhaust system and HAMMER PERFORMANCE 1250 kit

    Now we're getting somewhere! As you can see, the combination of IMPACT 560 cams and 10.5:1 1250 kit added a whopping 17hp to the top side of the dyno sheet, with essentially no loss anywhere. That's an enormous bang for the buck, as neither the 1250 kit nor the cams are very expensive.

    Keep in mind that you can't really do a 10.5:1 compression ratio with either the stock "W" or the JACKHAMMER 570 cams. Cam timing and compression ratio are closely tied together, and either of those cam sets at a 10.5:1 compression ratio will cause too much compression, resulting in detonation. Always run a compression ratio that's appropriate for your cam timing.

  5. Port your heads. You may be surprised to find head porting so far down the list, especially coming from a head porting shop. But the truth is, these late model heads are better than people realize. Although they vary from one set to the next, we've yet to come across a set that couldn't support 95+hp right out of the box, and some can support more than that as you can see in the charts above. So spend your money where it does the most good, and with these late model heads that means do the cams and 1250 kit first.

    But when you're ready to port the heads, we can put together very carefully matched combinations of head work, 1250 pistons, and CRUSH 600 cams that deliver in excess of 120 horsepower, for example:

    Dyno chart sheet for HAMMER PERFORMANCE 126 horsepower 1250 Kit Sportster Performance Package

    This is a 2007 equipped with a HAMMER 1250 kit, CRUSH 600 cams, SLEDGE head porting, an HPI 51mm throttle body, high ratio rocker arms, an Air Hammer air cleaner, a Patriot Defender exhaust, and a Powervision tuner. We're working on new developments to take this over 130hp as well. This is an enormous amount of power from a bolt-on kit!

    Bottom line, porting your heads opens the door to even more gains, when used in conjunction with a 1250 kit and cams. But just like cams and pistons need to be matched to each other, head work needs to be done in such a way as to match your pistons and cam as well. Often times, head work will cause the chamber size to grow, which then creates a need for more piston dome to avoid losing compression. This is especially true of big valve head work, and/or head work that's designed to accommodate high overlap cams, because those things create a need to "sink" the valves in their seats to gain clearance. The key here is that moving up the horsepower chain incrementally may create the need to buy some parts twice, like pistons, and pistons are not cheap. So try to do your heads, cams, and 1250 kit all at the same time to avoid this issue.

1988-2003 Models

Coming Soon!

1986-1987 1100 Models

Coming Soon!

Frequently Asked Questions

Coming Soon!

Final Thoughts

Coming Soon!

Free Web Counter