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Bafflle in or out for performance?

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Pugzilla
Barry Sheene
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Bafflle in or out for performance?

Post by Pugzilla on Wed 03 May 2017, 6:03 pm

Got a 350mm Delkevic silencer with a removable baffle.

Would the bike perform better with the baffle in or out?
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eternally_troubled
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Re: Bafflle in or out for performance?

Post by eternally_troubled on Wed 03 May 2017, 7:17 pm

Who knows? Smile I'd just pick the option that sounds best to you...

If having the baffle in/out makes a significant difference then I suspect you'll notice.

More significantly, I suspect no one knows...

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Beresford
the 900
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Re: Bafflle in or out for performance?

Post by Beresford on Wed 03 May 2017, 10:03 pm

For what it's worth, I have tried 3 different silencers on my bike. The standard black lump, a Yamaha Fazer 600 standard silencer and finally a straight through box. Without a doubt the pick of the bunch was the Yamaha item. Not straight through but not a constricted size tail pipe like the standard box. It was the same on the inlet side and outlet, unlike the standard box which is constricted down to a much smaller size outlet.

The Yamaha box was quite quiet at low revs but really howled higher up. It also seemed to me to give my bike a much stronger mid range than the other two. Unfortunately I dropped the bike and wrecked that box and haven't been able to find a similar replacement (yet Twisted Evil ).
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liverpool_f_
the 900
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Re: Bafflle in or out for performance?

Post by liverpool_f_ on Wed 03 May 2017, 10:56 pm

Generally speaking, it will flow more air with the baffle out. So for a given amount of fuel, as is provided by the fixed jetting in your carb, it will probably run optimally with the stock exhaust. An aftermarket exhaust and especially a one without a baffle will increase air flow without increasing fuel flow and therefore decrease power. Most power will be attainable with the freest flowing exhaust in tandem with a rejetting to get it back to optimal air/fuel mixture. In that case a freer flowing exhaust will allow more air AND fuel.
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Jameshambleton
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Re: Bafflle in or out for performance?

Post by Jameshambleton on Thu 04 May 2017, 7:23 am

I run mine without the baffle, I averaged 65mpg last month over 1781.1 miles so I'm not sure about the fuel use loss aspect. Though my bike has been on the back wheel (and in the air) more times that I can remember in the last month. 

As for the powerloss I'm not sure about that either, as I've got 51.33bhp at the rear wheel measured on the dyno last year and that's with a +2 size rear sprocket which only increases torque I got 38.37ft.lb and the stock is 33.9ft.lb
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trevor machine
the 900
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Re: Bafflle in or out for performance?

Post by trevor machine on Thu 04 May 2017, 7:57 am

I only have one comment to make and sadly it's not very relevant to the core of the OP's question - which I suspect is about top speed and acceleration. However, taking "perform" in a broader context, I think I'd be tempted to say that the cb500 doesn't perform quite as well with the baffles of after-market exhausts removed. This is because there is noticeable "fluffiness" at low speed - which becomes most apparent around town and when filtering, etc. Also when cold running. Nevertheless, this and accompanying slight sensations of "hunting" etc., are very easy to 'ride around' and don't cause any real difficulties at all.

I suppose if you're a smooth running Nazi zealot - and they do exist - it will play on your mind, like a tongue repeatedly probing a broken tooth. Such bike-owning types can become a bit OCD about even the slightest running issues - e.g. why is this bike's idle very slightly lumpy, even when warmed up? Answer - probably because you spend ten times more hours cleaning and worrying about it than actually riding it. Get out on it, get some fresh petrol through it, rinse, repeat, etc. And then it will either be totally cured, OR it will be exactly the same - but you'll have adjusted to its traits and no longer care about them because you're enjoying the bike just as nature intended.
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Pugzilla
Barry Sheene
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Re: Bafflle in or out for performance?

Post by Pugzilla on Thu 04 May 2017, 3:16 pm

Is it normal to hear some backfiring, a few pops and bangs, when coming off the throttle?
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geewhizz
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Re: Bafflle in or out for performance?

Post by geewhizz on Thu 04 May 2017, 5:17 pm

I feel like the peak power is a little bit lower down the rev range with the baffle out. I find myself slower with the baffle out too. Could be due to the noise however.
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trevor machine
the 900
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Re: Bafflle in or out for performance?

Post by trevor machine on Thu 04 May 2017, 5:40 pm

Pugzilla wrote:Is it normal to hear some backfiring, a few pops and bangs, when coming off the throttle?

Mine's like being strafed by a Gatling gun. Yet the other hardly makes any extraneous noise on the overrun. Both CB500s are running the exact same Fuel can, w/out baffles. Suffice to say I much prefer the former. So much commotion - especially going down hills off the throttle. It's like flying a gunship in Vietnam. Kind of. ; - )
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trevor machine
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Re: Bafflle in or out for performance?

Post by trevor machine on Thu 04 May 2017, 5:41 pm

geewhizz wrote: I find myself slower with the baffle out too. Could be due to the noise however.

I find myself faster. It's like the bike's egging me on.
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Jameshambleton
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Re: Bafflle in or out for performance?

Post by Jameshambleton on Thu 04 May 2017, 5:54 pm

Pugzilla wrote:Is it normal to hear some backfiring, a few pops and bangs, when coming off the throttle?
This is the only reason why I bought the bike so uh.... I guess so. get it right with the throttle and leve it slighty open when you're going down hill and it sounds really nice.... unless you don't like it then don't do it Wink 
geewhizz wrote:I feel like the peak power is a little bit lower down the rev range with the baffle out. I find myself slower with the baffle out too. Could be due to the noise however.

Peak torque is 7-8k rpm.
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stormbringer
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Re: Bafflle in or out for performance?

Post by stormbringer on Thu 04 May 2017, 5:58 pm

Pugzilla wrote:Is it normal to hear some backfiring, a few pops and bangs, when coming off the throttle?

Ooohhhh yeahhhh!

The OE can does a grand job of hiding this, while eg a Fuel unleashes the hounds Smile
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Vardypeeps
Two Tone
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Re: Bafflle in or out for performance?

Post by Vardypeeps on Wed 10 May 2017, 12:55 pm

Pugzilla wrote:Got a 350mm Delkevic silencer with a removable baffle.

Would the bike perform better with the baffle in or out?



It all sound and seems to make no difference on the CB500 compaired to other bikes.
I do have a bigger dead spot at 4.5k-6k revs but picks up nice as it revs harder

I got the best pops and bangs at 6-7k when its nice and warm

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