| Author | Message | ||
     Loki |
Piston combos with XB heads on the tubers? What work will be required? Cut for T-storms, drop on for S1s, XB pistons into a tuber.... | ||
| Aaron |
They're made for 10:1 with a flat-top ... so they'll drop onto any non-thunderstorm tuber with no changes (i.e. 91-97 all models, 98 S1 (not S1W), 98 M2) To put them over a Thunderstorm piston (i.e. 98 S1W or S3 or all 99-02 models), you need to cut a 15 degree squish band into them to match the 15 degree dome. Angled squish bands like this are, IMO, a better way to do it. We also do a lot of them with 30 degree squish bands, and of course we sell pistons with 30 degree domes. The nice thing about the XB/XL1200R chambers is they have lots of material to work with, we can do whatever we want without having to molest the head. The TS heads by comparison have a very rough, uneven, cast-in squish band, and we typically have to shave .040 or more from the head to square it up and even it out. Cutting so much off introduces a whole new set of issues, like reducing valve to piston clearance and forcing the customer into custom pushrods. But there's no other way to do it on a Thunderstorm. We don't have that problem with the XB/XL1200R heads. To get these onto a tuber, you also need to drill and tap the breather holes (unless you use an XL1200R head) and also do something with the front motor mount, as the right front hole is moved inward 1/4". We have a mount available that solves that issue nicely. From Buell, the heads are only available bare, with seats & guides installed. But we sell'em fully assembled for the same price as the factory gets for all the parts. Plus we include far superior high flow stainless valves, deck squaring, and drilling & tapping of the breather holes for no extra charge (takes the CNC machine about 60 seconds to mill, drill, and tap one of those holes!). There's a small extra charge for cutting an angled squish band into them. | ||
| Loki |
Aaron, Thanks for the extra info. How about putting the XB12 pistons onto S1 rods. If it is possible, would there any value in it vs. cutting the head for T-Storms. | ||
| Aaron |
Oh, it's very possible, and it'd work fine. But I'm a big believer in angled squish bands like the T-storm pistons have. Unshrouds the valves and also directs the fuel being squeezed out of the squish bands more directly at the flame front. The T-storm pistons have a 15 degree dome angle, which is good. We also do a lot of 30 degree angle stuff, which unshrouds even better and directs the fuel even better. The trade-off with the 30 degree is that you give up squish area at a given dome height, resulting in less turbulence. Therefore it's better suited to taller domes and resultant higher compressions, IMO. | ||
| Loki |
Aaron, Thanks again, now to do some thinking and budgeting. Now if you only had the time to write a book. | ||
| Bluelightning |
Aaron, Is there any way to "clean up" my pistons, since i have my motor torn down? They are not damaged, I just want to remove the crap that is built up on top like this:  and this:  | ||
| Aaron |
Bead blasting is the most effective way. Be sure to put tape over the ring lands, though. Ring lands are a sealing surface and you don't want to change the finish. | ||
| Bluelightning |
Thanks. I'll give that a shot this week. Finally got all the parts. Heads are ported and new valve are cut in. Just need to finish the pistons, get the new studs put in, and put her all beck together. We'll see what the ole butt dyno says before taking it to the real dyno.  | ||
| Loki |
Guru Aaron, Since the S1 is down for an extended time..... I have seen the difference between the S1(flat top) and T-Storm pistons. Is the XB12 a flat top or domed like the 9 I have sitting on my desk? Do the 9 and 12 share a common pin height? From my reading, the 9 only had a change in the crank and rod to get the destroke. Just trying to get things straight in my head... | ||
| Aaron |
"Is the XB12 a flat top or domed like the 9 I have sitting on my desk?" Flat. "Do the 9 and 12 share a common pin height?" Yes. Also the same bore. The XB9 has a rectangular dome to match the XB bathtub chamber. It needs some dome to get to 10:1 under that head (same head as the XB12) because of the shorter stroke. "From my reading, the 9 only had a change in the crank and rod to get the destroke." That is an accurate statement. The XB12 has a 3.8125 stroke with a 6.926 rod length. The XB9 has a 3.125 stroke with a 7.270 rod length. The difference in those rod lengths is equal to half the difference in the strokes, to put the piston in the same place with the same compression height. | ||
| Loki |
Thanks Aaron. Now you made me want to ask this next question. What would the result be with a 9 piston and the 12 stroke? I know the compression will go up. But would it go through the roof? Might there be other concerns. Just being curious and like thinking too much some days. If I am treading on thin ice let me know... | ||
| Aaron |
People do it all the time. 12:1 or so. But there are better ways to do it, IMO ... 30 degree .250 dome would get you there with a much better chamber shape. | ||
| Loki |
Probably not the best combination for a daily streeter. I had an iron head sport with 13:1 once. Affectionately known as the leg breaker. No electric gizmos, just plain kicker. I realize that the forward thinking people in East Troy were thinking future. The 9 being a stepping stone for the 12 and Sporty to follow. Thanks for opening up the book of info and wisdom. Bry |
