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sniperelite

Exhaust resonance

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sniperelite
Hi!
 
I installed a Leovince full exhaust on my FZ-07, but it makes an awfull resonance sound when i let off the throttle.
Can i fix this in any way (nothing to complicated) ? I have that exhaust for 2 yrs now and i accepted my fate long ago, but no one could give me an answer.
youtube link:
go to 1:12min!
 
 

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norcal616
The burble you hear when you rapidly close the throttle is normal...an ECU reflash or a fuel controller will smooth out the burble...

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sniperelite
The burble you hear when you rapidly close the throttle is normal...an ECU reflash or a fuel controller will smooth out the burble...
I'm aware of the burble sound and don't mind that, but i mean that irony resonance sound you hear before that sound. 

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level41
Did the exhaust work on a stock system, or you bought a fuel controller?

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sniperelite
Did the exhaust work on a stock system, or you bought a fuel controller?
No fuel controller, but dealer made it run richer (don't know how) 

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r1limited
Its the nature of the crossplane
 
I am no physicist but I will argue it anyway :)
 
Every thing that moves creates a point of resonance
 
From Wikipedia, the free encyclopedia
This article is about resonance in physics. For other uses, see Resonance (disambiguation).
"Resonant" redirects here. For the phonological term, see Sonorant.
Increase of amplitude as damping decreases and frequency approaches resonant frequency of a driven damped simple harmonic oscillator.[1][2]
 
In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies.
 
Frequencies at which the response amplitude is a relative maximum are known as the system's resonant frequencies or resonance frequencies. At resonant frequencies, small periodic driving forces have the ability to produce large amplitude oscillations, due to the storage of vibrational energy.
 
 
 
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rider
Its the nature of the crossplane  
I am no physicist but I will argue it anyway :)
 
Every thing that moves creates a point of resonance
 
From Wikipedia, the free encyclopedia
This article is about resonance in physics. For other uses, see Resonance (disambiguation).
"Resonant" redirects here. For the phonological term, see Sonorant.
Increase of amplitude as damping decreases and frequency approaches resonant frequency of a driven damped simple harmonic oscillator.[1][2]
 
In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at specific frequencies.
 
Frequencies at which the response amplitude is a relative maximum are known as the system's resonant frequencies or resonance frequencies. At resonant frequencies, small periodic driving forces have the ability to produce large amplitude oscillations, due to the storage of vibrational energy.
 
 

I kind of knew what resonance was, then I read this. Now I have no idea what it is and my brain hurts. I ain't got none of that college book learnin'. Nice research job, though.
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gregjet
The use of the word "resonance" is conjunction with an exhaust is problematic as there are two separate ( though somewhat related) meanings already attached to the word when it comes to exhaust systems.
One is the physics associated with tuning the exhaust/ engine system for optimium engine power output.
The other is muffler tech and eliminating ( or enhancing) "noise" and not power output related , but compliance ( aesthetic?) related.
I am assuming you are referring to the latter.
Are you referring to the little backfires/dead sounds?

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sniperelite
The use of the word "resonance" is conjunction with an exhaust is problematic as there are two separate ( though somewhat related) meanings already attached to the word when it comes to exhaust systems. One is the physics associated with tuning the exhaust/ engine system for optimium engine power output.
The other is muffler tech and eliminating ( or enhancing) "noise" and not power output related , but compliance ( aesthetic?) related.
I am assuming you are referring to the latter.
Are you referring to the little backfires/dead sounds?

nope not the backfires, i don't mind that. it's the high pitched tin can-like sound when i let off the throttle. Maybe the gopro filtered out the loudest parts but in real life it's so loud you can get a headache. 

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gregjet
Yeah, sorry , I can't hear anything that shouldn't be there. Quite possibly the recording quality ( or lack thereof) of the sound. Most cameras have very poor sound pickup profiles.

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norcal616
might be a foot lever rattling or the kickstand spring with the resonance... on the FJ-09 forum there was this odd high pitch buzzing upfront around the dash area that was traced to the clutch lever rattling around- solution was a thin plastic washer to take up the wiggle room...
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gregjet
Just though of something else. It is not uncommon for spot welds to be incorrectly placed or missed on the internals. This can cause some rattling/ banging/ buzzing at some resonances or all.
 

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r1limited
Just though of something else. It is not uncommon for spot welds to be incorrectly placed or missed on the internals. This can cause some rattling/ banging/ buzzing at some resonances or all.
That happens to me a lot just listening to all the voices in my head. 
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topazsparrow
I'll jump in the dog pile here and suggest that OP is referring to the metallic rasp noise on decel / throttle cut. You can here it precisely between 0:26 and 0:27 on the above video.
 
I would argue that it's just a characteristic of that particular exhaust set up. I don't hear anything like that on my Akrapovic system nor on the stock system.
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