View Full Version : Anyone know if a S1 exhaust will fit a s3?

5th October 2008, 04:02
Hey guys,

I need to find out if it is possible to bolt on a s1 exhaust on a s3. Any advice is greatly appreciated.

5th October 2008, 14:07
Onto a 97-98 S3, yes.

Onto a 99-02 S3, no.

There was a change in the frame in '99 and the rear head pipe was changed to go under the frame instead of over it. So headers don't interchange across from 98 & older to 99 and newer.

5th October 2008, 14:14
Thanks. I should have put the year. I've got a '99 and was watching an auction for a s1 exhaust.....looks like it won't work. Thanks again.

5th October 2008, 14:36
A couple other things on Buell exhausts ...

The outlet of the '98 and earlier header is in a slightly different place than the outlet of a '99 and newer header. As such, a '98 & older muffler doesn't properly fit a '99 & newer bike, and vice-versa. I've seen people do it, but it places stress on the whole system.

Buell's in general, and tubers in particular, are notorious for their exhaust system problems. Brackets break, header studs break, pipes crack, etc.

These issues got a whole lot worse in 1999. Besides the changes in the header already discussed, there was one other change that was made to the header that year, the elimination of a little twisted tab bracket that connected the header to the front shock mount.

Basically what was happening is that the 99 & up header was allowed to move around quite a bit more. That causes flexing of the pipe to head connection, and flexes the header studs. Buells are known for those header flange nuts coming loose. Guys would go double nutting them, or using self locking nuts to keep them on. But really, it was just fixing the symptom. Sure, you could do things to keep the nuts on, but eventually the stud just breaks, from too much flexing.

So anyway, Buell recognized the issue, and in '01 or '02 (my memory is fading) they came out with a new front muffler mount. This new one is shaped like an upside-down "Y", with two bushings, one on each side of the muffler bracket. This cleaned up the problem a LOT. Not 100%, but it helped a lot.

Anyway, if you don't have that mount, I highly recommend you get it. If you go to buy a new bushing for the old style mount, the part number supercedes to the new mount.

At one time, they were giving the new mount out for free as part of a goodwill program. I got like 4 of them because I owned 4 tubers at the time. But I think that program is long gone.

5th October 2008, 14:41
Oh, one more thing ...

On domestic bikes, the Thunderstorm motor included a header with a bigger collector. The outlet is 2-1/2". Non-Thunderstorm bikes had a 2" outlet.

Thunderstorm motors came out in '98, on the S3 and S1W models. '98 S1's (non-W's) came with Lightning motors and the 2" header.

For '99, all the bikes got Thunderstorms, and hence, a 2" header outlet.

But the same is not true of international bikes. I don't about the international S3's and X1's, but I know the 99-02 international M2's got a 2" collector (although they still got Thunderstorm heads). They also got Lightning cams, where all the domestic M2's got "D" cams.

5th October 2008, 14:50
The S2 is a different animal. They had standard Sportster motors, not Lightning or Thunderstorm motors. They also had a unique header. The head pipes were longer and the collector came out under the bike, instead of in front of it. As such, the muffler is different as well. The front bracket is attached to the header instead of the muffler. The muffler has a rear bracket only. The collector outlet/muffler inlet is 2".

The Buell Race Kit header, if you can ever get your hands on one, is like this too, with longer head tubes and the outlet under the motor. It uses a real short muffler. The collector outlet/muffler inlet is 2-1/2". It's really one of the better exhaust systems you can get for a tuber, although it's not particularly durable. Part of the issue is that front mount is clamped on instead of welded, which allows too much movement.

This chart:


shows what the race kit header can do in a bike like yours. This is a '99 X1, same motor and fuel injection as yours, although it has a Power Commander and some motor work. The point is, the torque curve is a nice wide parabola, pulling over a wide rpm range. That's what most folks want from a street exhaust.