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TxOutlawRider

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Reply with quote  #1 
Ok, Ive been wondering about this for awhile now, and maybe someone out there knows something about this.

  I've got a CT Exhaust and Ive got an endcap that allows me to slide open a little hole in the end for when I'm racing.  So I was wondering why someone hasn't built some type of pressure operated valve that would open and let the exhaust flow more only when the motor needed it.  HMF offers different size tips with their Comp exhausts, so its quiet when you need it and powerful and loud when you want it to be.  My CT can be made really quiet by taking a bunch of disks out, but I lose top end.
  I'm thinking a butterfly valve like off a throttle body that you could adjust to only open as much us was necessary (like a CV carburetor).  In fact, I may even try that (I have a valve body base and butterfly laying at the house) and play with the tension on the spring until it only opens when I have enough RPMS.  That way you could make it dead quiet at idle and low speeds and loud only when the motor is wound out.

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2007 Outlaw IRS

"Outlaws are the Chuck Norris of the quad world."
Beorn

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Reply with quote  #2 
They do that with super cars. It should work just be careful what way the dump valve is pointed.
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07 525 irs
- pro - flow intake w/ k & n filter
- Yosh RS-5 Exhaust
- DWT rear beadlocks
- DDM HIDs
(Mine is on the right)
- +++

LEOGM5150

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Reply with quote  #3 
that is an interesting idea. that could work well for riding through areas where you do not want to draw attention to yourself.

on a butterfly i think the exhaust would have the same pressure on the side closing it as on the side opening it. you may need it to have some sort of mechanical advantage to get it to start open.

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FROM: POWELL WYOMING USA

MY GREATEST FEAR IS THAT WHEN I DIE MY WIFE WILL SELL MY TOYS FOR WHAT I TOLD HER I HAVE INTO THEM...

2014 POLARIS RZR 4 900 EPS
2012 POLARIS RZR 4 900 XP
2008 POLARIS RZR 800
2008 POLARIS OUTLAW 525S LE
2007 POLARIS OUTLAW 525 IRS
2000 400 RCR TWO STROKE SCRAMBLER
2001 400 TWO STROKE SCRAMBLER
2005 SKI DOO 1000 TWO STROKE SAND SLED
TxOutlawRider

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Reply with quote  #4 
A spring operated flapper valve would almost work, but with all the bouncing around a quad does, it'd be bouncing open and closed all the time I think.
I'd also think a cheap electric cutout would work if I could figure out a way to trigger it by engine rpm. Maybe have it open above 7000rpm or something?

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2007 Outlaw IRS

"Outlaws are the Chuck Norris of the quad world."
ScramblerXLE

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Reply with quote  #5 
Varying backpressure as a function of engine RPM would cause some interesting challenges from a jetting point of view.  May be able to get it close enough to work though.  I assume what you're after is noise reduction and not power right?  Because adding a bunch of backpressure will hurt power.
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-Walt GNCC # 728 (GNCC - Vet A)
2015 KTM 525XC
2009 KTM 525XC
2009 KTM 450XC
2009 KTM 250XC
2005 Predator 558 (project)
2003 Cannondale 440 (project)
2006 KLX 250S
2002 Scrambler X 500
Sold, crashed, or otherwise gone: 2008 YFZ450, 2005 Predator 500 LE, 2007 Outlaw 525, 2003 Cannondale 440
TxOutlawRider

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Reply with quote  #6 

Im really not thnking of adding any backpressure, i just want it to bleed off any exccesive back pressure.  Im thinking that out exhausts are a compromise.  If they build it so its quiet, it chokes off the exhaust as the rpms build, and if they build it so its open enough to make top end power, then its too loud everywhere else.  So if it was built correctly it would be allot quieter at idle and gradually get louder as the rpms build, and at the same time making big power on the top end because of the reduced high rpm back pressures.


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2007 Outlaw IRS

"Outlaws are the Chuck Norris of the quad world."
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