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Exhaust confusion.

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Simba76
Renault 5 Driver



Joined: 17 Dec 2014
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PostPosted: 15:56 - 01 Oct 2015    Post subject: Exhaust confusion. Reply with quote
I have an sv650 with a beawulf end can.
When i bought the bike it had no baffle in it. Due to my living/ working situation I bought a baffle from beawulf themselves. Screws in simply as it should.
Doesn't sound any quieter, hmm maybe a tiny bit, but where the bike was running "breathless" before, this seems to have been improved apon fitting the baffle.
How does this work?
I thought it was running rich as I could smell fuel when I started it up.
Would the baffle improve the running??
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MCN
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Joined: 22 Jul 2015
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PostPosted: 16:17 - 01 Oct 2015    Post subject: Reply with quote
How did you measure the difference in sound between the baffle in and the baffle out? I think the other name is Decibel (dB) Killer.

You might not notice the difference just by the 'sound' alone. You need to use a device to measure the dB it make in and out.
The measurement of sound is not straight forward but baffle in and out can be 10 dB difference


There is a specific standard procedure for this test so everyone is on the same page. Purely because one man's quiet is another man's racket.

Noise Limit

The baffle can affect the power slightly. But only in extreme conditions.
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stonesie
World Chat Champion



Joined: 04 Jul 2010
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PostPosted: 21:39 - 02 Oct 2015    Post subject: Reply with quote
It's to do with the back pressure in the exhaust, too little and it will run lean and that can also cause a poor burn and fuel smell from the exhaust. It happened to mine when I fitted a stubby can and it lost some mid range so I re-fitted the longer can. The earlier carbed bikes were a bit more sensitive to it as the later injected bikes have a bit of scope for adaption with the lambda sensor...

You could get the carbs cleaned and re-jetted, a bit of dirt in the jets could lean it off a touch and removing the baffle takes it further.

https://imageshack.com/a/img684/425/dscf0290b.jpg
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Rogerborg
nimbA



Joined: 26 Oct 2010
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PostPosted: 22:10 - 02 Oct 2015    Post subject: Re: Exhaust confusion. Reply with quote
Simba76 wrote:
I have an sv650 with a beawulf end can.

Carb or fuel injection?

What have you done to ensure that the fuelling hasn't being mullered by dicking around with the exhaust?
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Ariel Badger
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Joined: 02 Dec 2006
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PostPosted: 22:40 - 02 Oct 2015    Post subject: Reply with quote
If I run my bike on an open pipe with no can she hits 111 Db. If I put my stubby can on with no Db killer it is only 98 Db. All testing done by a ACU Scrutineer.
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RhynoCZ
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Joined: 09 Mar 2012
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PostPosted: 23:29 - 02 Oct 2015    Post subject: Reply with quote
Ariel Badger wrote:
If I run my bike on an open pipe with no can she hits 111 Db. If I put my stubby can on with no Db killer it is only 98 Db. All testing done by a ACU Scrutineer.


The diameter of the inner pipe is what makes the difference. I've got a smaller diameter open pipe, mate has got also an open pipe, but bigger diameter. His can makes a terrible noise, mine is quite. Thumbs Up

Simba76 wrote:
but where the bike was running "breathless" before, this seems to have been improved apon fitting the baffle.
How does this work?
Would the baffle improve the running??


Yes, simple stuff, the db killer makes your exhaust a bit more restricted and the side effect of that is the ''effective'' torque moving down to the low/mid-range. That's probably how the engine was tuned (with the OEM exhaust), then you put open exhaust on it (lets more air through the engine at given time), which moves all that to the top end of the rev range. I found out about it, when I had open exhaust on my GPz. With the db killer, the engine felt strong at low revs, and with no db killer the engine became unusable at low revs, but oh boy the power at the top. Twisted Evil

That's what the power valves were made for, to have something that restricts the exhaust at lower revs and opens it at high revs to give you the best performance possible.
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Simba76
Renault 5 Driver



Joined: 17 Dec 2014
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PostPosted: 08:07 - 03 Oct 2015    Post subject: Reply with quote
Roger- Its the Carb'd model.
I am unsure if it was tuned/dicked about with or without the new Can, but from the feeling of improvement with the baffle/ restrictor in, I'd say it had been set up with the standard Can and then not touched after the New Can or Baffle removal.

The smell of fuel, I'd always imagined it was running too rich.
I've changed the air filter and will be changing the plugs this weekend work allowing.
I'll give the old plugs a good scrutineering to see what they tell me.

My next steps will probably be a carb clean.
I have an idea the bike was standing for a month or two before I bought it , except for a run to get an MOT.
It had the low fuel light on when it got it so any crud at the bottom of the tank may have been used.
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-Current bike ......
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