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To loud? :-(

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skatefreak
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Joined: 06 Feb 2010
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PostPosted: 11:10 - 21 Jun 2016    Post subject: To loud? :-( Reply with quote

Sooo,
I have an old CBR600 F3.
It came with a Yoshi and sounds the nuts.
I also have a stock exhaust for it and although its a lot quieter it really really kills the mid range.

After the first track day (had to ride home to swap the exhaust to stock, turns out our db meter is way out) I rebuilt the Yoshi to put a wider perforated steel pipe through the middle to fit a baffle in there.

This brought it down to 101 at the last track day but the chap there said it was close and may not pass on a dry day (it was raining at the time).

Soooooooo.
Is there anything more I can do with this pipe to quieten it down (can fabricate as I had to rebuild the entire steel internals in the pipe a few years back) without messing up the power delivery?

I'm still not 100% happy with the Yoshi with the baffle in there as it pops a lot and power delivery around the 5,000 range is very very choppy (holding constant power around a corner in the wet and can feel the back wheel squirm a bit).

Admittedly the carbs do need balancing (idles a bit choppy).

Alternatively, would this exhaust do the trick, bringing the noise level down without harming performance or am I going to have to consider looking in the carbs?

There are many drilled bolts on the frame of the bike (allegedly a sign on track use), so is there a chance the engine has been jetted for the exhaust and that's why using the stock exhaust seems to hit the performance so much?

Any thoughts would be very much appreciated Very Happy

Can't wait for another dry track day Laughing Laughing Laughing
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robertw95
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Joined: 22 Nov 2014
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PostPosted: 11:58 - 21 Jun 2016    Post subject: Reply with quote

Luckily never been noise tested here in Scotland, you can try getting a proper baffle from somewhere like mhp, conditions play a huge part in noise testing I have heard always make sure that the bike is hot when testing this can make quite a difference.
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skatefreak
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Joined: 06 Feb 2010
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PostPosted: 13:18 - 21 Jun 2016    Post subject: Reply with quote

My main concern is that the Yoshi was pretty badly corroded when I got it, so when I rebuilt it to the same specs, the internal tube was only around 28-30mm and that's far to narrow to get a standard baffle in there.

I'm yet to find a baffle for that model of yoshi Shocked
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supZ
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Joined: 03 Feb 2009
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PostPosted: 16:00 - 21 Jun 2016    Post subject: Re: To loud? :-( Reply with quote

skatefreak wrote:
is there a chance the engine has been jetted for the exhaust and that's why using the stock exhaust seems to hit the performance so much?

quite possibly.

with that in mind your best bet is probably get an exhaust you can live with (the stock is awful) that's not silly loud and get it dynajetted to match. this'll solve all your problems i'd say.

my steelie trackbike just had a venom end can on. never failed a noise test and never had any power issues either.
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