Stock exhaust modification..."core" the can's, or make repackable?

[chris1044]

Current bike (m1000ds) has the stock low mount cans that have been half cored...they sound absolutely terrible aside from the fact that they are louder than stock (raspy as hell around 4-5k - likely due to the half-assness the P.O. did to them as the center tube touches where he "cut" )

So, tonight I started to core them, but after cutting the ends off of them, I can't help but ask why people don't make these things into straight flow through can's with packing?? Similar to what you'd have with an aftermarket can I suppose.  I'd end up cutting roughly 10" off the can's to get past the plate welded internally to hold the three "tubes" together, and because of this I'm concerned that in the long run it's going to end up too loud...If I end up going this route, I'll use some high quality packing (very experienced on this with off-road bikes), but I really don't want the thing to be super loud.

Anyone have any advise/thoughts??  Worst comes to worst, I'll just have to make my own internals and utilize the aluminum sleeve as the actual exhaust...stick with the stock lenght, but make it a single tube with packing....

[suzyj]

I looked at doing similar work to the exhaust on 695, which I believe is the same as that on your m1000ds.

The issue with mine is that it's extremely difficult to remove the aluminium sleeve.  There's a lip on the bottom end to provide extra cornering clearance that stops it from sliding off the back, and the curve of the pipe that goes to the header means that you can't push it off the other way either.

So the only options are to either cut the tube that goes to the header and have it tigged back on afterwards, or else keep the sleeve on, which effectively limits you to modifying only the last chamber.

If you find a better way, I'm all ears.

[chris1044]

I have access to a TIG, so that is what I was considering.  However, if I could find some type of "seat of the pants" info from people regarding how loud the cans are if they're shortened all the way to the first chamber, and then packed, I'd just go that route...otherwise I need to worry about cocking when re-welding, etc...becomes more of a hassle than it may be worth.  I've also thought about doing a "full core" and then plasma-cutting the separator between the two main chambers as well..

What did you end up with all said and done if you don't mind me asking...again, I'm not looking for overly loud - I'd rather it quite so it doesn't attract a ton of attention.

[suzyj]

What did you end up with all said and done if you don't mind me asking...again, I'm not looking for overly loud - I'd rather it quite so it doesn't attract a ton of attention.

I haven't done anything as yet - I've been plenty busy doing suspension and brake upgrades.  I'd be very interested to hear what you end up doing though.  Like you, I don't want an excessively loud exhaust.  My ideal would be just a couple of inches shorter than stock, and just a tad louder.

[booger]

I have completely gutted the cans on my bike and replaced with fiberglass packing, and it sounds great. No worries about that at all. Just do a thorough and complete job of it and it will be fine. Although I did this to an S2R800, I imagine one would have similar results with a dual-sided swingarm bike, even mellower with the giant cans that come on those things. Perhaps take the opportunity to shorten the amazingly huge mufflers a bit?
For an HD video of the sound:
http://ducatimonsterforum.org/index.php?topic=35964.0

[chris1044]

Bergdoerfer:  I read through your entire link, and that's exactly what I was thinking of doing, almost to a T....I've got a ton of off-road experience, and that's essentially how all re-packable offroad silencers are, so why wouldn't it work here?  And yes, if I go that route they'll be getting cut to roughly 10" in length...I just wanted to make sure they're not uber loud.

After listening to your video, it does sound pretty good, but you can't really get a feel for the overall "loudness" of them...you said you had termi's at one point...were your stock can's done like that louder than them?  And if so, by how much?


Right now I've got my can's cut down to within 2" of the seperator/baffle plate in them, and I'll likely run them like that for this weekend just because I want to ride.  I've thrown them on as they are (no beauty ends on them) and can honestly say that cut like they are now they sound somewhat quieter than the piss poor "half core" job that the P.O. did....likely because that extra chamber isn't there for the sound to just deflect all around in.


Assuming your stock can's weren't much louder than the termi's, I'll be chopping mine down even further and going the same route you did...if I do this I'll post pics/how to

[booger]

Since the Termis I used to have fitted had essentially the same construction, I cannot say which was louder. They are basically the same. Can't go wrong with some cored stock cans if you do them correctly.
However 10" may be a bit short. Might want to go 12" at least, aren't those stockers like 2 feet long or something? If it were me I'd line the tips up with the seat lock. Shorter you go the louder it gets I think. 

[chris1044]

Right now they're (the outer Al sleeve) is roughly 13" give or take a few 32nd's.  The problem that I foresee is that to get past the inner baffles I'll need to cut another 2"-3" off them, and then there's what appears to be a "half" baffle that's used as the final chamber in the original design (stock outlet tube attaches to this).

I'm going to ride it for the weekend as is, but plan to work with them next week...and yes, the shorter you make them, the louder they get, even with packing.

[suzyj]

Could you get a die grinder in there and remove the guts with that?

[chris1044]

So I just got done putting them back together/riveting the end caps back on them.  Again, they're 13" long, cut roughly 1-2" above the plate closest to the end. I was able to cut the remaining length of the tubes out of it using a dremel tool. They don't sound that bad now, my raspy sound is all but gone.  However, they're still somewhat heavy, and I just can't leave well enough alone...

After really looking at the can's, there's more than one "baffle" welded into it...so the idea of simply cutting the can's short enough to get past the main plate is out.  Even with a plasma cutter I don't think you could trim the insides enough.  I think the easiest way to turn them into re-packable can's would be to eliminate the entire steel can all together; use a die grinder to carefully cut the aluminum outer can where it's chamfered so you can slide it entirely off the steel can.  Then, cut the steel can so it's roughly 1-2" long, put the Al can back over it, rivet it together and tig the piece you cut off of them back on, then pack them like what bergdoerfer did to his, them rivet the end caps on.  Sounds like a PITA, and it will be, but in doing this you'll loose a ton of weight from the can's, should have a decent sound, and they'll still look "clean" (not a fan of carbon fiber...).

I'm going to brainstorm on this for a while, and I'll eventually get it done.  When I do, I'll take pictures and post them as a "how to"....it may be after the riding season is over though. 

[jc.cyberdemon]

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mine have nothing in them and cut about halfway, they really aren't that loud and i think they sound good.