Hitting the Pipe Catalogue

Duke 690 Akro are known to loose power with larger baffle / removed baffle.

Edit: other pipes are often noted in power charts with baffle out it make more power, making more desire to rem9ve for max power.
 
bartiger said:
Akra full system on Duke 690 has full power with installed eater, and less with removed
Click to expand...
Hello Bart, I'm very surprise of that. Where did you get that information? The Pirate?
It's very interesting for me because the next regulations for racing in France will be 95 dB (for 2024).
I was thinking to a largest silencer or put back the baffle (much simplier solution).
 
This is common knowledge based in many dyno runs from many different people on many different dynos over many years... nobody wants to believe that because its contrary to general assumption.

The original DB-eater makes the least noise and the most power.

Larger DB-eater makes better sound, and less power.

No DB-eater makes best sound and least power.

This is going from the point that the bike is in the best state of tune in each setup... a full tuned bike with no db eater will have much more power than stock, and a full tuned for with db eater will have more than with no db eater.

I am sure that a phd with fluid dynamics or thermopajamas or something can explain why.
 
It is difficult for me to explain in English but it is possible that the db killer acts as a counter-cone (like for 2 strokes).
Some guys who ride with me to the french supermono championship have on their prototypes exhaust pipes with counter-cones before the silencer.
Hope you can understand what I write.
 
I used to ride an FZ07 and we had many, many posts on db-killer in vs out and how they affect power. Many riders got their ECU flashed at 2WDW and they had many instances to choose from to develop their opinion. As conveyed to me, it's dependent upon motorcycle and exhaust. Some with the killer in make more power, some with the killer out make more power. It's very specific to the motorcycle, modifications and exhaust.

I own the Akra exhaust for the KTM 690 and have installed it. WITH the killer in, it is too quiet, and you cannot hear the exhaust at all. With it out, it is perfect. How did it affect power? No way to know, but I think that having two silencing chambers on this exhaust and not just having a pass-through midpipe will likely lead to better perf without the killer. But that's just supposition.

At the end of this season, I will get out to 2WDW to have it dyno'd and tuned. We'll see.
 
I think I'll go back to the dyno this winter to see the difference with (and I have two different dB killer) and without and maybe with a larger silencer if I find someone to try (a Spark for example).
 
I may try the delkevic one

delkevic.co.uk

Delkevic Limited

Delkevic have been active in the manufacture and supply of motorcycle silencers, exhaust systems, and accessories for over 5 years. Our online shop offers quality affordable slip on silencers, full exhausts systems, and exhaust accessories combined with our dedication to outstanding customer...
delkevic.co.uk delkevic.co.uk
 
FaNaTic said:
Hello Bart, I'm very surprise of that. Where did you get that information? The Pirate?
It's very interesting for me because the next regulations for racing in France will be 95 dB (for 2024).
I was thinking to a largest silencer or put back the baffle (much simplier solution).
Click to expand...
Yes, pirate mentioned it in one or two videos about the full akra, and in the video with this exhaust on the Vitpilen 701.
Maybe you could try the original Akra slipon for the Vitpilen instead of the Duke can. It got a little more Volume..
But isn't your intake louder then your exhaust?
 
FaNaTic said:
It is difficult for me to explain in English but it is possible that the db killer acts as a counter-cone (like for 2 strokes).
Some guys who ride with me to the french supermono championship have on their prototypes exhaust pipes with counter-cones before the silencer.
Hope you can understand what I write.
Click to expand...
Is this something like FMF power bomb? I mentioned something similar an many pitbike exhaust
 
bartiger said:
Yes, pirate mentioned it in one or two videos about the full akra, and in the video with this exhaust on the Vitpilen 701.
Maybe you could try the original Akra slipon for the Vitpilen instead of the Duke can. It got a little more Volume..
But isn't your intake louder then your exhaust?
Click to expand...
The intake without lid do it worse for sure.
We still are at 102 dB for 2023 but if we still compete in 2024, I will go to the dyno for testing the different solutions (lid, baffles) for the 95 dB.
It’s too bad I understand even less German than English. I miss a lot of things in the Pirate’s videos.
 
FaNaTic said:
The intake without lid do it worse for sure.
We still are at 102 dB for 2023 but if we still compete in 2024, I will go to the dyno for testing the different solutions (lid, baffles) for the 95 dB.
It’s too bad I understand even less German than English. I miss a lot of things in the Pirate’s videos.
Click to expand...
do you still have the original airbox? if you wanna try some stuff on dyno i be happy to provide you some of my 3d printed parts for testing..
you can write an english email to pirate racing, they are likely to answer soon.. info@pirateracing.de
 
Hello Bart. My airbox is stock, without lid.
Why not testing a special part (a lid I presume).
I have to be sure before to go there that the guy of the Dynojet get a good sonometer and the right procedure for the mesurement.
 
Is there a special procedure to measure or just at the finish line of each track?
Today I found some Infos on the Akra and db killer.
The right db killer has low back pressure in low refs bit makes enough back pressure to shorten the virtual length of the exhaust, what leads to a better "fulling" and more peakepower at high refs.
Without db killer you could get a bit of low end power but wil loose topend.
It's an information from a KTM tuner named Highscore at the KTM forum
 
Thats what had me confused, normally db at a track, or outside, is different than inside right, because reflecting the walls can impact the result?
 
Of course, the measurement must be done outdoors without walls close and without other noises.
But I think the guy who has the Dynojet bench will also do the noise measurement (outside of course).
Anyway, a new procedure will be defined along the new 95 dB limit.
 
Currently, it is at the exit of the track (after the race).
The noise mesurement device is at 1 meter and 45° of the silencer and the revs level depends on the engine.
 
You must log in or register to reply here.
Back
Top Bottom