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Just spent 10 hours making up a new exhaust set up for my bike. This is for my race bike. What i have now is a 620ieSS. It is being set up to run in a restricted v-twin class. There isnt a hell of a lot of things that we are able to do to the bike before they get upset. One of the few things we are allowed to do is change the mufflers.

Well, i got about to weighing up my old mufflers and found out they were about 10kg (give or take) So i thought that instead of replacing both with light weight carbon jobs, i would swap them over for just a single side can. I found a photo on the "post your supersport" photos section that i liked and though, hey, why not.

Shopping all over town and everyone that i went to see said.. Not interested, or yeah sure, $1200 + 4 weeks minimum! That kind of put a damper on it. It looked like i was going to have to just suck it up and pay the $1200... until the last guy i went to said... try this mob, he will sell you the parts to do it yourself!

$90 in parts and i went out and bought myself a mig welder. And im still $500 better off and now i have a mig welder as well! Well, thats how i sold the idea to my wife anyway!...

Having not fabricated anything in quite a long time (7 years working in a casino will do that for your fabrication skills...) It was turning out to be a nightmare... But i managed to get the hang of the mig welder again and off i went...

Anyway, long story short, 10 hours later i dont have a cross over piece any more and im now all happy single sided. Lost over 10kg of weight off the bike and only have to pay for one exhaust!

Next time i think i will buy a tig welder, as the mig was a nightmare to weld up exhaust tubing :)
 

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Yeah, this is a great idea. I have a friend who is a really good welder and he's working on my bike now. I bought a carbon fiber muffler as well, and he's using SS tubing. The only difference is that mine is going on the left side of the bike instead of the right side. The reason is to keep the exhaust heat away from the rear brake M/C. I'm going to have the finished pipe coated by Swain Tech also, since the wind from a bike will cool off the exhaust a lot more than it would in a car. So, keeping heat in the pipe would seem to be even more important on a bike than in a car. I agree that two mufflers are not needed, too much weight and complexity. We tested a mock up of the system yesterday and it's not any louder than the oem pipes. The tone is just deeper because the pipes and muffler are fatter. We are also using most of the original exhaust for this project.
 

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That looks great. I just got a 2001 project bike and want to change the exhaust also. I'm looking at either a single or double but want a megaphone (old) style. I used to stick weld many years ago but not sure if I could do MIG. Well done!
 

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nice idea, i was wondering to do the same thing, but i am not very good in soldering :D
One question, you cut the horizontal cilinder header right?
 

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I love my dual Remus cans and would never go single but daaammnn..
NICE JOB!!!


Also on the "Well, thats how i sold the idea to my wife anyway!"
 

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I love my dual Remus cans and would never go single but daaammnn..
NICE JOB!!!
I think there is a tradition at Ducati for dual mufflers. I guess they are supposed to symbolize the twin cylinders or something, but in reality two mufflers are entirely unnecessary and just add weight and complexity. Even many Superbikes have dual mufflers, but why? I see the Aprillia only use one for many of their bikes.
 

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Discussion Starter #7
Yeah... I just cut the front cylinder pipe off just before the polution plug. Thought, why make up part of an exhaust i dont have to make. Next time i make one i will make a stainless system from manifold to exhaust out of much thinner metal and TIG it up instead of MIG.

I went for the single look as well after i remember seeing the old SuperMono race around Eastern Creek about 15 years ago. I love the sound of it. I guess this is my Supermono mock up. I know, i know, the muffler is on the wronf side for a supermono. I just found it easier on the SS to run it out this side away from the chain. There is nothing eally that matters on this side of the bike where the muffler runs.

I am going to get it ceramic coated once im happy with it and how it runs and then i wont have to worry about the amount of heat. But at the moment, there is still a fair bit of space between the rear master cylinder and the collector. I tried to keep all the distances roughly the same so the standard fairings would fit back on. (May still require some "adjustsments" to the fairing yet...)

What i would really like is a set of the airtech SuperMono fairings for the bike. Only problem is that i live in Australia and they charge about $8000000 for postage of anything from the US to Australia... Woe is me... might look into it though :)
 

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Discussion Starter #10 (Edited)
Thanks sledgrehammer... Your photos on the supersport photos page is what prompted me to go out and start getting orgainsed... Thanks for the how to photos as well, as i will be sure to use these next time i do my next set of headers... My collector was made by me, but the ones of the burns site look super nice and easy to fit.

As for more power with two cans, i find that hard to believe. Have you had a look at the crimped down X connector for the pipes, its looks rank. And any performace gain by running the dual system is surely lost in the extra kilos it has to lug around. And try and tell me the SS doesnt look better with a single can... Although a nice pair of custom hi rise cans comes a very very close second. Underseat exhausts on the SS although, do not :)
 

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Seems I've seen where Ducati's produce more hp w/ twin exhaust. TT
It's all about flow. If one muffler is fitted, then it should have a larger pipe after the collector than having two of them. I'm sure there is some math I could do to show this, but I'm too lazy to do that now. The engine doesn't care if there are 1, 2, 3 or 20 mufflers, as long as the flow is there and the pipes are close to equal length.
 

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It's all about flow. If one muffler is fitted, then it should have a larger pipe after the collector than having two of them.
Yes and no. It has to be a bit larger than in 2-1 system but not much. It depends on what you want. If your goal is hi revving max hp engine, then piping have to be large enough. In my case i wanted more mid range torque and a bit more in max hp area. It seems that i succeeded. If your piping (from collector to muffler) is too large you end up losing a lot of torque. I can't remember diameter of the collector to muffler pipe, but it was very conservative. I can measure it if somebody wants to know it. It is a bit larger what i had in primary pipes. I planned to use a lot larger pipe, but fortunately i have a friend who knows these things and warned me about that. Then he helped me to choose right size tubing.

About flanges. I bought them from Germany (ricambi-weiss).
http://www.ricambiweiss.de/product_info.php/info/p425_CA2-SATZ-KRUeMMERFLANSCHE--DUCATI-FUeR-400-600-750-900-SS.html/XTCsid/o279m69l8ods9k0qkq1pdjuhv5
 

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Two mufflers on twin-cylinder bikes do make more power than 2-into1 systems. Do you really think Ducati runs two pipes/mufflers on their WSBK machines to add weight or look cool?
 

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Exhausts are not just a pipe to let the gases out!

There is quite a bit of science to exhaust pipes and muffler design. I have been reading a brilliant book by Phil Irving, the designer of the Vincent V twin engine, and amongst many things exhaust design.

When the exhaust valve opens, the gas is at higher than atmospheric pressure and exits as a slug of gas. This slug has some momentum and draws more gas to help evacuate the cylinder. When the slug reaches the end of the pipe, there is a pressure wave reflection that can induce negative pressure when it reaches the exhaust valve, thus drawing out more gas and if inlet valve opening suits, it creates negative pressure, thus helping suck in more air/fuel.

Pipe length and diameter influence this effect, as does muffler length and even the end shape length and diameter. Even this book that was last published in the 60s noted that racing engines had short pipes and megaphones or maybe straight through ( Mmmm reminds me of shorty systems on some GP bikes) It goes on to say that some pipes can be too short, so the solution is to double the calculated length to retain the "natural frequency' of the system. In particular short pipes tend to boost performance at high RPM, which is where most true race bikes are run, but at the expense of lower rpm performance.

I presume this is also why some bikes may not perform so well with aftermarket slipons - sound great, but noise does not give more usable power across the day to day rev range.

Similarly, inlet tract tuning/length is also important. I forget now which brands, but some vary the inlet tract length depending upon RPM.

I suggest reading a bit of theory, before wielding the mig/tig or gas axe if you are chasing performance over appearance.

Too late at night now, but I will scan the basic info and post it on this thread.
 

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Two mufflers on twin-cylinder bikes do make more power than 2-into1 systems. Do you really think Ducati runs two pipes/mufflers on their WSBK machines to add weight or look cool?
The number of mufflers has almost nothing to do with how much power is produced by any engine. As long as the system is tuned to the engine's desired power curve, then it will produce the power as intended. There is nothing that says two mufflers make more power than one, as long as each is tuned and sized appropriately.

Bikes that come with V twin engines and ONE muffler:
KTM (some models)
Aprilia (some models)
Buell (don't know about all models)

and others...
 

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There is quite a bit of science to exhaust pipes and muffler design. I have been reading a brilliant book by Phil Irving, the designer of the Vincent V twin engine, and amongst many things exhaust design.

When the exhaust valve opens, the gas is at higher than atmospheric pressure and exits as a slug of gas. This slug has some momentum and draws more gas to help evacuate the cylinder. When the slug reaches the end of the pipe, there is a pressure wave reflection that can induce negative pressure when it reaches the exhaust valve, thus drawing out more gas and if inlet valve opening suits, it creates negative pressure, thus helping suck in more air/fuel.

Pipe length and diameter influence this effect, as does muffler length and even the end shape length and diameter. Even this book that was last published in the 60s noted that racing engines had short pipes and megaphones or maybe straight through ( Mmmm reminds me of shorty systems on some GP bikes) It goes on to say that some pipes can be too short, so the solution is to double the calculated length to retain the "natural frequency' of the system. In particular short pipes tend to boost performance at high RPM, which is where most true race bikes are run, but at the expense of lower rpm performance.

I presume this is also why some bikes may not perform so well with aftermarket slipons - sound great, but noise does not give more usable power across the day to day rev range.

Similarly, inlet tract tuning/length is also important. I forget now which brands, but some vary the inlet tract length depending upon RPM.

I suggest reading a bit of theory, before wielding the mig/tig or gas axe if you are chasing performance over appearance.

Too late at night now, but I will scan the basic info and post it on this thread.
I am very much aware of pipe tuning, exhaust gas scavenging and other important factors in the design of exhaust systems. The diameter of the header pipe has a large influence on the shape of the horsepower curve, for example, but this has nothing to do with the number of mufflers on the engine.
 

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I can tell you that there was a bit of planning before welding. My exhaust isn't even ready yet. Next thing is welding "torque sleeves" in primary pipes. After that i have to find hot spot from collector to muffler pipe and there comes little step which will decrease backflow. I can quarantee that even now without those changes my system beats stock headers in every area. That is tested fact.

If i spend big amount of cash in Sil-motor spaghetti headers and cans i can get 3-5hp more. Woud you guys pay 700e (1000 usd) for getting 3-5hp? You can't even notice that when driving. I rather put that money in NCR cams and that is going to make some difference again. I already got 80rwhp with way too rich mixture (a/f 11.0). Now i have sorted it out and my bike goes better again but i haven't dynoed it yet.

Others talk and others weld and try. I will continue trying. I haven't got negative results yet so i'm willing to try more ;)
 

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Video about 2 into 1 vs. 2 into 2 exhaust systems. This is directed at Harley Davidson motorcycles, but probably applies to all V twin engines:
http://odeo.com/episodes/23359567-Exhaust-Systems-and-Performance-2-into-1-vs-2-into-2
I realize of course that the oem Ducati exhaust is not a 2 into 2 system as discussed in this video. I don't know what you would call the oem Ducati system, but it does seem to behave like a 2 into 1 type.
 

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Here you can see dynosheets of my first two runs. First was red and completely without mapping. Green lines are after rough mapping without lambda. I had a bit of bad luck on my dyno day because lambda was broken. Then we just decided to map it so that it wouldn't run lean in any circumstances (because i had trackday next day). I also had way too large valve clearances because of new valves and valveseats. Now that thing is sorted also. When everything is sorted out i believe i could get close to 85rwhp with standard cams.



After that day i bought Innovate LM-2 lambda meter and since that i've been mapping it all the time. I can log RPM, TPS and A/F at the same time so it's easy to get everything right. I haven't touched ignition yet. As you can see from the curve, 2-1 design isn't that bad. Especially HP curve is now very nice. I also believe that i can sort out that flat spot in torque curve just before 5000rpm by adjusting the ignition. My ignition maps is the same that comes in DP-ecu.

Anyway, it can't go wrong if you ditch your stock system to a trash can ;)

Edit:
Torque is in Nm...
 
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