zxfingyz
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posted June 23, 2005 06:37 AM
 Edited By: zxfingyz on 23 Jun 2005 10:29
Resonators on ZX-12
Can someone tell me what the "resonators" do?
  
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pdb1964
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posted June 23, 2005 07:42 AM
It resonates? Sorry.
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k bryant
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posted June 23, 2005 09:03 AM
Depends on the context of how you are using them. For instance, in exhaust technology for cars, "resonators" are something we put in front of of the mufflers to help attenuate sound before hitting the mufflers. They are kinda like a "glass-pak"; a smaller thin muffler that helps take the edge off the exhaust noise, but really does not affect power too much. There are many applications that simply require more sound damping than what a muffler can provide. Many late model cars come with several resonators in-line, in-front of the actual larger volume muffler.
Many OEM motorcycle exhaust use similar technology. If you remove a stock muffler, you can sight down the s-bend/mid-pipe and see that most have perforated core material in there. This is a similar version of a resonator type affect on helping cancel sound waves before hitting the muffler. By incorporating this, they can in effect build a less restrictive muffler that will still meet the 80 dbA limit. Of course most couple this with an exhaust flapper valve as well that restricts exhaust flow at lower rpm's.
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zxfingyz
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posted June 23, 2005 09:26 AM
Awsome! Thanks for the reply.
I should have given some context for the question.
I took off the farings to get to my newly leaking radiator and hanging off the ram air tubes is these plastic reservior looking things that the service manual(DFI 2-3) calls resonators. Air flows down into these cans near the radiator from the ram air and then back up into the engine warmer or cooler maybe?
For what? More/less air pressure?
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k bryant
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posted June 23, 2005 09:47 AM
Edited By: k bryant on 23 Jun 2005 10:49
Hmm.... Good question. Professor Doug Meyer would probably know much better than I on that example.
I do know that intake noise is almost as big a problem as exhaust noise when you are trying to cancel out the last few decibals (EPA 80 db limit). I've done many certifications where the bikes are seemingly making more intake noise and spiking the meter, than exhaust noise. Buell's are a prime example. That's one reason why the changed to those huge airboxes. They could not pass the EPA cert with the smaller airbox because of way too much intake noise when the throttle was wacked WFO. Early year GSXR's had the same problem and had to compensate with more restrictive mufflers.
But I would be completely guessing if those resonators you're seeing/talking about have anything to do with sound.
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frEEk
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ummm... yeah
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posted June 23, 2005 10:27 AM
i'm pretty sure i remember reading the resonators were for intake noise attenuation, as suggested by k bryant. i'm thinking they may provide some function in terms of keeping water out of the airbox too, as water droplets may fall into the resonator and drip out the bottom, rather than continue along the intake.
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zxfingyz
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posted June 23, 2005 07:29 PM
Makes sense as there are small holes at the bottom of each of them.
I wonder what removing and blocking them will do for performance?
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frEEk
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ummm... yeah
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posted June 23, 2005 11:12 PM
again, if i remember correctly, i read there is zero performance gain from removing them. as always, that is open to debate and proof.
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rac4it
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Bergie
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posted June 24, 2005 04:19 AM
No gain on the dyno without vs. with, yes I tested this 4 years ago on a Dynojet 250.
What does that mean? Nothing really since a dyno can't simulate ram-air pressures at +/- 200mph. Therefore I left them ON, as the Kawasaki engineers intended. Yes I had them in place when I went 204 at Maxton.
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zxfingyz
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posted June 24, 2005 07:22 AM
That right there is good enough for me. They go back on today.
Thank you.
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MadMike
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posted June 24, 2005 12:29 PM
Yea but what if he would have run 208 with them off?????? we will never know will we?
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psycho1122
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posted June 25, 2005 07:46 AM
They are designed to resonate at a certain frequency when air flows over the top of the hole.
Just like blowing across the top of a beer bottle. Depending on how much beer is in the bottle will determine at what frequency it will resonate at.
KHI sized the resonators to produce a frequency at a certain air flow rate to cancel out the resonate frequency of the snorkel tube.
Mine are IN PLACE. However, I capped them off with electrical tape. This helps improve seal at the grommet and I get all the sweet noise from the snorkel.
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rac4it
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Bergie
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posted June 25, 2005 03:07 PM
MM is right, that is why I said my dyno testing didn't really mean anything because it was not measured in the real world.
If I have some time, and my runs are consistant enough for comparisons, I will do a back to back comparison at Maxton and post the results. I'm doubting there is going to be any improvement with the tubes removed, but we wont know until it is actually tested.
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psycho1122
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posted June 26, 2005 07:53 AM
Make some plugs for the holes in the tubes.
I agree on the consistantcy issue. IS Maxton the right venue to test the resonators?
What about the 1/4 mile?
Maybe a GPS "time over distance in one gear" test would be more consistant than either.
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zxfingyz
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posted June 28, 2005 06:44 AM
This might be a little ( or a lot ) niaive but don't you think we could just call someone at Kawasaki and ask them? I trust someone from KMC lurks here, y ou know who you are  why don't you just hook it up?
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Ra12r
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posted June 29, 2005 04:11 AM
I remember JC saying that removing the ram air tube affected his testing of Entropy's bike.
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entropy
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posted June 29, 2005 08:10 AM
quote:
I remember JC saying that removing the ram air tube affected his testing of Entropy's bike.
dropped 4-5hp on the dyno!
i ain't fukkin' with the ram air system no-mo'; kwak knew what they were doing, so my OEM system went back on resonators & all (bye-bye, Hans carbon snorkel)
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psycho1122
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posted June 29, 2005 07:16 PM
Hmmmmmm.....
Sounds VERY familiar to me!! 
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