XS11 exhaust system

[Boneswig]

Firing order on an XS is 1243. So if I want the bobber sound, would the correct exhaust header setup be 1-4 and 2-3? If I worked it out right I will get my bobber to have that single fire sound since I will have a VERY short delay per side while idling? Or am I looking at it the wrong way?

[crazy steve]

It's a four cylinder motor... it will never sound like a twin.

[Boneswig]

Agreed on that. Woulda been awesome but not possible. But here's the theory. If I (theoretically) split the motor. Having one fire left the next fire right, then left and then right. So i'll have a silent pipe on every fire on the motor. So agree that it is a four and a 4-1 is the better option, but won't the sound of the motor be different at idle by splitting to the different sides of the motorcycle? I don't know that's why I'm asking and giving the theory.

[crazy steve]

Exhaust sound has more to do with exhaust design. Be aware that the XS exhaust is not modification friendly. I've been on this site for years, and no one has successfully used an open exhaust and gotten the tune right on one yet...

You could possibly change the firing order with a set of custom camshafts (firing two cylinders at once) to get the 'sound' you're after, but what that would do cam chain harmonics probably wouldn't be good.

[Boneswig]

Hear what you are saying on that one, so the dual chrome side pipes will be more of a look than a sound. To reconstruct cams etc, don't know if it is worth the effort. I have heard that the xs11 has one of the toughest cranks in the world, but don't know if it could take a punch like that. It is something to think about but don't know if the effort is worth the result

[DiverRay]

The "spagetti pipes" (sp) that were once available are split 1,4 & 2,3. Special Ed has a set on his bike, and it DOES sound a little different. Not a lot, just a bit.
The NUMBER ONE thing on this bike is back pressure. On a 2&2 system, I would think single tubes of equal length that end about at the drivers foot pegs, the muffler from there, and a 1 1/4" outlet on the muffler, with a baffle/packing combo. That should give you the sound, and performance, that you want. Just a SWAG on the system, but should be close.

[1887]

I am not sure what the firing order is of an XS11 but I assume it is 1-3-4-2. Are you proposing firing 1&2 simultaneously then 3&4 together at a 360 degree interval? This would totally change the forces applied to the crank bearings which were designed to have compensating forces. The next obstacle would be cooling as it would no longer be evenly distributed and could over tax a air cooled design.

[Boneswig]

Driverray is on the same page I am. Hahaha. I was thinking of putting a nice set of megaphones (one on each side) and splitting the pipes as I worked it out was 1-4 and 2-3, ending up with a dead pipe on each spark. Over here there is a megaphone with adjustable baffles on the market, was considering them and then just adjusting the back pressure until I have both sound and performance. It's going to have to be balanced on both. Fortunately a bobber over here is not build for speed so I can lean more towards the sound side than the performance side

[Boneswig]

87, yes there will be a lot of complications in that cam conversion. After it was said, I also sat wondering about heat, big ends etc. Nice thought but won't be possible. It will kill the motor very quickly

[crazy steve]

The bottom end would take it, and cylinder heat would be another non-issue. Valvetrain harmonics would be the real problem...

[1887]

I have Jardine spaghetti pipes on my bike. People tell me it sounds like an air cooled Volkswagon Beetle, I can't decide if that's a compliment. To me the difference in sound is small compared to regular pipes.

[Boneswig]

To be honest I have never heard a four running on sp's, I will try and look around and see. I saw that the Honda 954 has a split up (similar to what I am considering) to the ex-up, but then joins into a single pipe from there. I will take some measurements on a set and see if it will fit on the xs. Then it is basically just re-routing the pipes to the back.