2002 1200S heads for performance?

[sharkoilfield]

Back many years ago I built a 100HP/88FT LB 2001 Sporty that was an absolute blast to ride... I've enjoyed touring on Dyna's since but still miss the lithe performance of a well built Sporty... I've found a 2002 1200S  and am wondering what kind of basis for performance the 4 plug heads might provide? Also; the accompanying ignition; is it suitable for a 100HP built 1200?  I see Sportster.org is gone.....

[gasshawg]

I own a 2000  1200S and love it. Never had it on a dyno. has the early model heads on it. Not much to brag about but does run low 13.00's with a street tire. Don't know when they change second plug placement. I like the stock ignition with the SE box,I have be told by the head builders it's all in the heads,cams,compression.Mine it still stock motor,and cams,has HD dealer 2 into 1 with my own collector,E-carb  extra spacers in intake to get carb in the air,NO head work.If you had one in the past and liked it I would buy it.

[aswracing]

The 1200S heads are basically a dual plugged, black highlighted version of the Buell S1 Lightning heads that were introduced in 1996. We started referring to these as "Lightning" heads many years ago, not only because of the Buell model, but also the very first over-the-counter versions had a "Lightning" script scribbled across them, which was later changed to Screamin Beagle. So these were basically the original SE Sportster heads, the very first generation of performance head HD made for Evolution XL's. The second generation was the Thunderstorm heads which came out in 1998, and then the XB heads which came out in 2003 and made it onto all XL1200's in 2004.

The Lightning heads have the exact same ports and valve sizes as the 88-03 XL1200 hemi head. Way back in the day, the SE catalog claimed 10% more flow or some such nonsense, but as someone who's flowed lots of them, I can tell you the range of results is no different from any standard hemi head, and the ports and valve sizes (1.715/1.480) are identical as well.

The only difference between the Lightning head and the hemi head is the chambers. HD added material and a 10 degree cast-in squish band that dropped the volumes down from 67cc (hemi head) to 62cc. They only ever paired it with a flat top though so the squish shelf didn't actually do anything. But it gives about 10:1, where the hemi head gave about 9:1 over the same flat top. That's the sole thing about the Lightning head that adds performance over the hemi head.

Although you can get 10 degree pistons that work with the stock chamber, the cast squish shelf in the chamber is really rough and uneven, so it's impossible to get a good squish clearance. You basically have to deck the head to remove the overhang around the perimeter of the chamber and then machine the squish band. We usually do it to 30 degrees.

The other thing is the valve shrouding. The way the material was added to the chamber causes some shrouding, and when you increase the valve sizes and/or sink the valves for clearance, it gets pretty bad. So you absolutely need to do a bunch of unshrouding work on this head.

But in the end, you can make a much, much better chamber out of this head than you can out of the hemi head. Here's a pic:


You can see how the head was decked, the squish band machined out to 30 degrees, the valve sizes are bigger, and there was lots of material removed from around the valves. All very typical stuff.

Even though you can make a decent chamber out of them, you're still dealing with a pretty bad port. The floor is low, the short side is terrible, and the long side is just about as bad, and you're missing the material you need to fix them right. So to make a really good port, break out the buzz box. Also, the seats can't handle much more valve than the heads came with, so you're looking at 4 seats to get some decent valve sizes fitted up. In the end you've got a lot of time and money into the heads, to get a decent result, for example:


This result actually came from that set of heads pictured above. The pipe makes a difference

In any event, as much work as it takes to make these heads good, a person is probably better off to just go get a set of the latest generation heads. They can be fitted to the older bikes easily, the stuff needed to do it is readily available. Really the only good reason to go through all this on the 1200S heads is to maintain the originality and stock appearance, which is what the above customer wanted.

[sharkoilfield]

Belated thanks for the concise info on Sporty heads. My 100HP Sporty utilized Thunderstorm heads done by HQ. What I was hoping was that there might be an advantage to the dual plugs but obviously proper design of the head comes first....also like the dual disc front anf adjystable suspension of the S. An 883R would work, too, if I was going to replace heads anyhow

[aswracing]

Y'know, I've fiddled with dual plugs a fair bit, and on Evo motors, I've yet to find one-tenth of a horsepower with them. Maybe I haven't set up the right conditions yet, but I've tried them on everything from flat top 3-1/2' bores to .500 dome 30 degree 4" bores. The motors have always wanted in the neighborhood of 5-7 degrees less advance when dual plugged, but the power number has come out the same when I do a back-to-back test, tuned for the configuration.

It's entirely possible though that they help reduce detonation. I don't really have a good way to quantify that in my testing. I just know I can't find power with them.

In my stable right now I have a 122hp 90ci Buell S1W, that has a set of dual plugged STD's on it, and I don't even use the right side plugs. Can't find a good enough reason to mess with it.

On my nitro bike though, I use them. It needs all the help it can get to light the fire, and if a plug melts down as they sometimes do, it's good to have a backup.

Ironheads are a whole 'nother subject. They respond really well to the second plug.

[sharkoilfield]

What I was thinking, too. Modified the spring in the VOES on my '01; that helped but was by no means a cure-all. Never had anything to do with nitro, but I understand it takes more to "light" properly. As for Ironheads, as with any old true hemi (my old 426) there's a big dome for that flame to get around, for sure...technology sure has moved on,eh?

[sfmichael]

good thread 

[WhipLash96]

The 1200S heads are basically a dual plugged, black highlighted version of the Buell S1 Lightning heads that were introduced in 1996. We started referring to these as "Lightning" heads many years ago, not only because of the Buell model, but also the very first over-the-counter versions had a "Lightning" script scribbled across them, which was later changed to Screamin Beagle. So these were basically the original SE Sportster heads, the very first generation of performance head HD made for Evolution XL's. The second generation was the Thunderstorm heads which came out in 1998, and then the XB heads which came out in 2003 and made it onto all XL1200's in 2004.

The Lightning heads have the exact same ports and valve sizes as the 88-03 XL1200 hemi head. Way back in the day, the SE catalog claimed 10% more flow or some such nonsense, but as someone who's flowed lots of them, I can tell you the range of results is no different from any standard hemi head, and the ports and valve sizes (1.715/1.480) are identical as well.

The only difference between the Lightning head and the hemi head is the chambers. HD added material and a 10 degree cast-in squish band that dropped the volumes down from 67cc (hemi head) to 62cc. They only ever paired it with a flat top though so the squish shelf didn't actually do anything. But it gives about 10:1, where the hemi head gave about 9:1 over the same flat top. That's the sole thing about the Lightning head that adds performance over the hemi head.

Although you can get 10 degree pistons that work with the stock chamber, the cast squish shelf in the chamber is really rough and uneven, so it's impossible to get a good squish clearance. You basically have to deck the head to remove the overhang around the perimeter of the chamber and then machine the squish band. We usually do it to 30 degrees.

The other thing is the valve shrouding. The way the material was added to the chamber causes some shrouding, and when you increase the valve sizes and/or sink the valves for clearance, it gets pretty bad. So you absolutely need to do a bunch of unshrouding work on this head.

But in the end, you can make a much, much better chamber out of this head than you can out of the hemi head. Here's a pic:


You can see how the head was decked, the squish band machined out to 30 degrees, the valve sizes are bigger, and there was lots of material removed from around the valves. All very typical stuff.

Even though you can make a decent chamber out of them, you're still dealing with a pretty bad port. The floor is low, the short side is terrible, and the long side is just about as bad, and you're missing the material you need to fix them right. So to make a really good port, break out the buzz box. Also, the seats can't handle much more valve than the heads came with, so you're looking at 4 seats to get some decent valve sizes fitted up. In the end you've got a lot of time and money into the heads, to get a decent result, for example:


This result actually came from that set of heads pictured above. The pipe makes a difference

In any event, as much work as it takes to make these heads good, a person is probably better off to just go get a set of the latest generation heads. They can be fitted to the older bikes easily, the stuff needed to do it is readily available. Really the only good reason to go through all this on the 1200S heads is to maintain the originality and stock appearance, which is what the above customer wanted.

So what you said here, does this also apply to the SE 55 cc heads?  Can the chambers be opened up enough to accommodate an 88 c.i with a dome piston?

[aswracing]

So what you said here, does this also apply to the SE 55 cc heads? 

No, absolutely not. That head came out in 2005 as the new SE head for rubber mounts, but they also came out with a bracket to allow it to be put on the 91-03 bikes too. The ports, seats, and valve sizes are identical to the stock production 04-06 XL1200 head, which is essentially the XL version of the XB head. So it's a decent head, but it doesn't flow any more than stock.

Really there are two and only two things about that head that are different from the stock head of that generation:

• They milled .050 off the deck to get the chamber size down to 55cc. Remember, an XB or 04+ XL1200 head is already .020" shorter than your original '96 heads, so now you're talking about a head that's .070 shorter than where you started. Exhaust fit, manifold fit, valve to piston clearance, and pushrod length all need attention when you use these heads. Any more milling and you get into the seats, unless the valves are sunk. Then you get into a tail chasing mode. .050" is a manageable amount, but it's getting up there, pay attention to details.
• They fitted up stronger springs and stainless valves. Unfortunately, the spring pack they chose forced them to sink the spring pockets .120". Why in the hell they did that, I have no idea, there are plenty of suitable spring packs out there that provide travel without sinking the pockets. Anyway, the downside is that you better pay attention when working the roof of the port. It gets thin.
  

It's not a terrible head. But when it comes to properly preparing a head, I'd sure rather start with a stock one. The things they did to that head from the factory are not necessarily good things to do, and they're hard to undo.

Can the chambers be opened up enough to accommodate an 88 c.i with a dome piston?

Oh sure, depending on the piston. What we like to do is a 30 degree dome angle paired with dish in the middle of the piston. Here, let me show you some pics:



The 30 degree angle does a couple of things for you. First, it substantially removes the shelf that the air otherwise has to go around as it enters and exits the cylinder. This really improves breathing, particularly at the larger valve sizes. In fact, with these late model XB type heads, at a certain point you more or less hit a wall, on the flow bench, where going bigger in the valve does not increase flow unless you also 30 degree the chamber. The second big advantage is that fuel being squeezed out of the squish band has a direct shot at the flame front, without obstructions. When fuel gets squeezed out and hits a dome, it's forced to turn, which invariably causes some air/fuel separation. Removing the obstruction promotes better mixing and therefore a more efficient burn with less detonation.

30 degree domes and chambers are no big secret, they've been around forever, but mainly in race motors. Reason being, the steep angle reduces squish band surface area unless the dome is made tall to compensate, and of course a tall dome takes them outside the realm of pump gas. But in a street motor, you can overcome that limitation by dishing the middle of the piston as shown.

Now with a head that's pre-decked that much, you may have to do a little shorter dome. There's a limit to how deep the piston can be dished, at least safely. It's a matter of working the heads, fitting the bigger valves, sinking and unshrouding around the valves an appropriate amount for both v-v clearance and proper geometry with the cams to be used, machining the chambers, and measuring to see where they're at. Then selecting a piston with the right dome to work, possibly milling it a little, or worst case doing a custom.

It'd sure be better though to start with a stock head.

[WhipLash96]

So what you said here, does this also apply to the SE 55 cc heads? 

No, absolutely not. That head came out in 2005 as the new SE head for rubber mounts, but they also came out with a bracket to allow it to be put on the 91-03 bikes too. The ports, seats, and valve sizes are identical to the stock production 04-06 XL1200 head, which is essentially the XL version of the XB head. So it's a decent head, but it doesn't flow any more than stock.

Really there are two and only two things about that head that are different from the stock head of that generation:

• They milled .050 off the deck to get the chamber size down to 55cc. Remember, an XB or 04+ XL1200 head is already .020" shorter than your original '96 heads, so now you're talking about a head that's .070 shorter than where you started. Exhaust fit, manifold fit, valve to piston clearance, and pushrod length all need attention when you use these heads. Any more milling and you get into the seats, unless the valves are sunk. Then you get into a tail chasing mode. .050" is a manageable amount, but it's getting up there, pay attention to details.
• They fitted up stronger springs and stainless valves. Unfortunately, the spring pack they chose forced them to sink the spring pockets .120". Why in the hell they did that, I have no idea, there are plenty of suitable spring packs out there that provide travel without sinking the pockets. Anyway, the downside is that you better pay attention when working the roof of the port. It gets thin.
  

It's not a terrible head. But when it comes to properly preparing a head, I'd sure rather start with a stock one. The things they did to that head from the factory are not necessarily good things to do, and they're hard to undo.

Can the chambers be opened up enough to accommodate an 88 c.i with a dome piston?

Oh sure, depending on the piston. What we like to do is a 30 degree dome angle paired with dish in the middle of the piston. Here, let me show you some pics:



The 30 degree angle does a couple of things for you. First, it substantially removes the shelf that the air otherwise has to go around as it enters and exits the cylinder. This really improves breathing, particularly at the larger valve sizes. In fact, with these late model XB type heads, at a certain point you more or less hit a wall, on the flow bench, where going bigger in the valve does not increase flow unless you also 30 degree the chamber. The second big advantage is that fuel being squeezed out of the squish band has a direct shot at the flame front, without obstructions. When fuel gets squeezed out and hits a dome, it's forced to turn, which invariably causes some air/fuel separation. Removing the obstruction promotes better mixing and therefore a more efficient burn with less detonation.

30 degree domes and chambers are no big secret, they've been around forever, but mainly in race motors. Reason being, the steep angle reduces squish band surface area unless the dome is made tall to compensate, and of course a tall dome takes them outside the realm of pump gas. But in a street motor, you can overcome that limitation by dishing the middle of the piston as shown.

Now with a head that's pre-decked that much, you may have to do a little shorter dome. There's a limit to how deep the piston can be dished, at least safely. It's a matter of working the heads, fitting the bigger valves, sinking and unshrouding around the valves an appropriate amount for both v-v clearance and proper geometry with the cams to be used, machining the chambers, and measuring to see where they're at. Then selecting a piston with the right dome to work, possibly milling it a little, or worst case doing a custom.

It'd sure be better though to start with a stock head.

Ok. I should have a stock set of 883 heads. In comparison to the SE 55 cc heads. A better starting point?

[WhipLash96]

To get a hold of you directly Aaron,  how do I do that?

[aswracing]

To get a hold of you directly Aaron,  how do I do that?

Use the link in my sig

[WhipLash96]

Ok. I am on my phone most of the time. Can't see your sig. Lol