| Author | Message | ||
     Kcs2 |
Hello Everyone, I have a 95 S2 that is totally stock, and I'd like to gain some more horsepower. I was told to start with the heads. What do you think, the thunderstorm, or XB heads? From my understanding, the XB heads will require an adapter. Also, will my stock exhaust work with these heads. Thanks for your help. Neill | ||
| V2win |
Neill, The best thing to do is call that old guy over near St. Louis. He would be glad to take ownership of that ol yellow bike and you could go find a fast one.  | ||
| Rick_a |
My next project will be XB heads. I've talked to a few racers and tuners about the subject and all of them have told me almost the exact same thing...don't bother porting the existing heads, don't bother with Thunderstorm heads and pistons, XB heads are currently the best heads you can use. The XB heads have the best flow, the best combustion chamber shape, have lighter valves and springs, and cost less. They're just more hassle to install. Stock exhaust will work, to my understanding the only things that will be needed are a different motor mount and the carb mounting bolts need to be drilled out. | ||
| Dave |
$230 for the Nallin XB head motor mount...fairly substantial chunk of change just to use the XB heads. DAve | ||
| 1320 |
On the S2 it is pretty easy to use the stock motor mount..I tapped the left front mounting hole and then threaded a piece of aluminum rod and screwed it in the hole..offset just a little and redrilled for the XB bolt pattern..worked great! | ||
| Pammy |
We have gotten 120hp outta Thunderstorm heads for racers. (with stock displacement) I guess it DOES depend on who you talk to. | ||
| S2carl |
1320, got any pics?? | ||
| Aaron |
Neill, One nice thing about the XB heads on an S2 (or Sportster or 91hp Buell Lightning motor) is they're designed for 10:1 with flat top pistons. So unlike a Thunderstorm conversion, you don't need to change your pistons, unless of course you're boring the cylinders in which case you need to buy them anyway. With respect to the motor mount, it's the right front bolt hole that's moved (inward 1/4 inch). You can just elongate the bolt hole in the stock mount:   I personally would not try to move that bolt hole in the head, because when Buell moved the bolt inward, they eliminated the boss that used to be there to support the bolt. It sure doesn't look to me like there's enough beef there anymore. I highly suspect Buell moved the bolt inward like this because it was a failure prone area on previous Buell heads, and by moving it in they got some beef around it without having to make the head wider. I ran my M2 like that, with an elongated bolt hole, for several months and had no issues. But it bothered me, both from an appearance point of view and I was always wondering in the back of my mind whether or not it would break. So I developed a billet piece. I believe it's the strongest Buell motor mount on the market, and it's priced very competitively with the other available offerings. I wish I hadn't posted those pics of it, because those were early prototypes and since then I've worked really hard to perfect it, it's now a much prettier piece. Also, unlike the competition, every corner of it is radiused. Hold one of my mounts in one hand and the competition's mount in the other, and compare the prices, and I'll make a sale every time. The other thing you need to do is as mentioned, drill and tap the breather bolt holes. The heads have the bosses on them, this is simple to do. Also, you might want to paint them black and possibly highlight the fins. Your bike has black cylinders with highlighted fins. The heads have bigger fins and will overhang the cylinders more than your stock heads, most noticeable on the left:  The heads are only sold bare, you have to buy the supporting hardware separately and assemble them yourself. I'd sure lap the valves in. Your stock exhaust will bolt right up, as will your stock intake manifold and rocker boxes. Whether or not the stock exhaust constrains the motor is another question. So what do you get for all this trouble? The shape of both ports is quite a bit better. The floor of the XB intake port is raised substantially, and it improves the quality of the flow substantially. There are changes in the bowl area that go with this raised floor. Of course, this port shape can be replicated in any other Harley head, but you have to add material to do it. This is just a philosophy thing, we would rather start with a port that has the material already there, but obviously people are successful adding material as well. As far as performance goes, bone stock in our estimation they'll support 5-6 more hp than a stock Thunderstorm, assuming they've got the supporting components around them. Fully ported, well, I got this out of my M2 yesterday, with a 1250 kit and other supporting components:  And I ain't done, in fact I'm taking it back apart again this week. Ultimately I think I can get this thing north of 130hp with these heads. I know I can take it over 130 with aftermarket heads, but I want to do it with OEM heads, that's the market. I've never split the cases on that bike, never even had the engine out of the frame. Best of luck with your project. edited by Aaron on December 15, 2003 | ||
| Hobanbrothers |
I would go straight to the XB heads, much better head right out of the box! Lighter valves that do hold up, we have been punishing them for over a year now with very good results. Much better valveguide seal system, springs may need a little shimming for optimum performance, but the whole valvetrain is much lighter, going back to bigger valvestems and weight associated with them is going backwards in my book. We did develope a little different exhaust valve, but still retain the 7mm stem. It helps cure that dip in midrange of XBs. The XB heads out of the box can support some pretty big HP numbers, with a little messaging they are top of the line! You can install XB top rocker box and breather and help eliminate almost all of your oil misting out breathers also. Just a great system all around in my book. Your stock exhaust will work with these heads, but if you have not done anything starting there, you may want to look at more cost effective ways of gaining HP first. It all comes down to dollar to HP ratio. Intake & exhaust, etc. You are a ways away from the 120 RWHP the others are speaking of if everything is bone stock. Good luck with your adventure into HP. | ||
| Loki |
Aaron, Why must you make me drool so much. Got a business trip coming up. The after effects of it are a call for a set of XB heads. Loki | ||
| S2carl |
Aaron, Wouldn't the new 04 XL heads solve the black fin color and breather bolt hole issues and still give you the XB performance?? | ||
| Racerx1 |
S2Carl Yep, 2004 XL heads will work great. The 2004 breather bolt itself is pretty radically different however | ||
| 1320 |
S2Carl, Here is a pic of the mod on an S2 Motor mount that worked just fine for me. This is from the motor side of the mount. As you can see the S2 mount is alot beefier than later models and I just picked the side that looked to me would line up everything the best and also it looked like that side of the mount had the most meat for my purposes...  | ||
| Dasxb9s |
Neill... Just give it up and buy an XB12... and trade me my BMW R1100RA for that nasty slug slow tuber. Because I am a pal... and a fellow Mob member... I am willing take the short end of the trade. :-) | ||
| Kcs2 |
Everyone, Thanks for all of the advice!! It looks like I will go for the XB heads. Aaron, Do you suggest I use my stock pistons, or purchase new ones? Also, could you provide me with more info on your motor mount? John, If I ever decide to sell my bike you will be the first one I call. Dennis, You are willing to take the short end of the deal??? What a Mob buddy  Neill |
