Difference in Sportster heads

[FXDBI]

So what is the CC and valve sizes used in a 883  and 1200 sportster heads.  Bob

[aswracing]

So what is the CC and valve sizes used in a 883  and 1200 sportster heads.  Bob

All 86-present 883 heads came 49-50cc chambers. Early ones were a bathtub, I've seen these bathtub 883 heads as late as some 1989 models. But most you'll come across are hemi chambers:



All 86-present 883 heads came with 1.580" intake valves, and 1.350" exhaust valves. 86-03 were 5/16 stems. 2004+ have 7mm stems with beehive springs, but they're still 1.580/1.350.

The 1200 came out in 1988. From 88-03, most used a 67cc hemi chamber:



Valve sizes were 1.720/1.480, with 5/16 stems.

The exception to the above was the 98-03 1200S model (Sport). It came with a dual plugged version of what we call "Lightning" heads, which first appeared on the 1996 Buell S1 Lightning. Lightning heads came with a 62cc chamber. They have an angled squish shelf cast into the chambers, but they shipped with flat top pistons, so it didn't actually do anything. The extra material they added to the chambers to reduce the volume also ends up shrouding the valves badly. Same 1.720/1.480 valve sizes as the hemi head, and same crappy ports. Lightning heads were really the first generation of Evolution Sportster performance heads, but all they really accomplished as compared to the 1200 hemi head was an increase in compression.

Also it's worth noting that in 1998, HD came out with the second generation of XL performance heads, the "Thunderstorm". But it was a Buell-only piece, they never shipped it on Sportsters (although tons of them got put on Sportsters). Here, I have a pic of it's chamber:



It's pretty similar to the Lightning head's chamber, in that it has cast-in angled squish bands on each side. But they enlarged it back to 67cc like the hemi heads, to allow bigger 1.810/1.575 valves without shrouding. All the Buells that shipped with these heads had a small 10 degree domed piston to match, bringing the CR back up to 10:1. There are also nice improvements to the ports in these heads. The short side was made longer (higher floor), and the long side was made shorter (shorter roof). In fact, you can see the long side difference if you compare the above to the hemi head picture before it. Look down in the bowls near where those stamped numbers are, near the guides. Notice how the hemi head has a much sharper transition there, as compared to the Thunderstorm. In the Thunderstorm, they added material there to smooth that transition.

Moving along, in 2003 HD came out with the XB head, again it only shipped on Buells. But then all XL1200's got a version of the XB head starting in 2004. A slightly different version of these heads still ships on XL1200 models to this day. It has a 62cc bathtub chamber:



Valve sizes are still 1.810/1.575 like the Thunderstorm, but this is when the 7mm stems and beehive spring pack were first introduced. The same hardware would find it's way to Twin Cams in 2005, literally the same part numbers.

The XB head also had improvements to the ports. Again, they raised the floor to make the short side even longer than the Thunderstorm, and made the long side even shorter than the Thunderstorm. Again, look down in the bowls where the stamped numbers are, next to the guides, and compare that to the Thunderstorms. Notice how they smoothed that even more.

In our testing, a stock XB head is good for 4-5hp more than a stock Thunderstorm, despite showing about the same on the flow bench. The only thing you really notice on the flow bench is that it's a quieter port. The less difference between the short and long sides, the less turbulence you get. Also, it's flowing about the same, but it's doing it with less port volume. That generally results in more power.

More info on our web site here: http://www.hammerperf.com/ttxlheads.shtml

[Ohio HD]

That's first class info right there.         

[Coff 06]

Bob.        Ask and you shall receive            Good info,thanks asw.        Coff 06

[FXDBI]

Awesome that's a education there on sporty head. TYVM This will be a big help for my buddy to figure out what to do with his sporty. 72 and wants to hot rod it, doesn't use the internet. Guess I will have to get him online and show him this site.  Thanks again for the education!  Bob

[FXDBI]

Bob.        Ask and you shall receive            Good info,thanks asw.        Coff 06

Ya you have to just love this site for the wealth of knowledge here and the want to share it. Its the only Harley forum I follow be lost with out it.  Bob

[Pete_Vit]

Bob.        Ask and you shall receive            Good info,thanks asw.        Coff 06

Ya you have to just love this site for the wealth of knowledge here and the want to share it. Its the only Harley forum I follow be lost with out it.  Bob

now I see why my Son's Buell was a beast - great info, man I love this place

[harley_cruiser]

This should be a sticky in the Sportster forum.

[1FSTRK]

  For aswracing and for HTT

[aswracing]

Thanks guys, glad someone found my drivel useful.

I'll tell you what, between 883's and 1200's and Buells and 4-speeds, there have been so damn many versions of the Evolution Sportster head that all these little details about each type are not common knowledge. A guy isn't likely to know all these little things unless he works with them every day.

Another big set of details gets into the shallower chambers & longer valves on 883 heads and how that affects your decisions when it comes to pistons and valve sizes and cams. You've got to really be precise about how you do that combination to make sure it all fits together with proper compression and v-v & v-p clearances and works right and delivers power. But I'll spare you that discussion, it gets kind of obscure.

Which specific XL heads a guy has, in combination with his power goal, drives the entire approach to hopping up the motor. Some of the heads just aren't cost-effective to take above a certain level, so in that case you just tell the customer he has to replace them to get there. Other heads may suck in stock form, but can be taken to a high level with reasonable head work. And other heads are pretty good right out of the box and may or may not even need any head work to reach the customer's goal, depending on how much he's after. So that's always question number one, what heads do you have and how far do you want to go, everything else flows from that.

[Pete_Vit]

Maybe now I understand better why my Son's Buell was stolen, I'm sure it's been parted out 

[cyclobutch]

That's first class info right there.         

Yeah - for sure. Many thanks.