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DRZ250 noise with a yoshi

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Hey everyone,

in case you're curious...

I just put on a new Yoshimura RS-3 off-road pipe/header on my '03 DRZ250. Just for giggles, I had my bike sound tested by a State Park Ranger before and after the install... Before the new pipe, I had the stock baffle removed, 3x3, and a K&N filter.

before(stock system): 92.5 Db.

after (- yoshi baffle + cone type spark arrestor) : 102 Db!!!! :ride:

after (+ yoshi baffle/spark arrestor): 95.5 Db :thumbsup:

lesson learned: USE THE SOUND BAFFLE!!! I was surprized how much of a difference the baffle made in the sound, without any noticable decrease in power. I was surprised to learn how loud my bike was without the baffle! I knew it was louder, but I didn't think a DRZ would blow a 102!

Hmm, maybe that's why they put the baffle in the box!

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Is it possible for you to take a picture of the baffle and post it? Is it a series of endcaps, or something else. Back when I bought a Yoshi for my DR-Z250, all they had were several undcaps to choose from. If they have something else for sound reduction, I would be interested in seeing a picture.

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Hey everyone,

in case you're curious...

I just put on a new Yoshimura RS-3 off-road pipe/header on my '03 DRZ250. Just for giggles, I had my bike sound tested by a State Park Ranger before and after the install... Before the new pipe, I had the stock baffle removed, 3x3, and a K&N filter.

before(stock system): 92.5 Db.

Stocker with the baffle still in is always under 89. :thumbsup:

The way I've always understood it is each number point higher (i.e. 90 to 91) is 10 TIMES LOUDER!!! It's like how earthquakes are measured.

But any 4 stroke under 96 with an aftermarket exhaust is a good thing. Anything we can do to keep the riding areas open is a good thing!

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Check out my mods page, I posted some new pics that show the baffle and the cone type spark arrestor I had without the baffle (although noise still made it illegal).

http://www.thumpertalk.com/forum/garage.php?do=viewvehicle&vid=2893

The reason I had it sound tested without the baffle is so now everyone has a definitive answer to: "Does the baffle really do that much? Why should I bother with it, it takes away power and doesn't quiet it down that much"

I couldn't notice any power decrease with the baffle, so there's no reason not to use it!!! And it's not like the baffle quieted it down by a few decibels, it was 7.5 Db quieter!!! That was the difference between being blatantly illegal to more than legal, with a huge gain in power over stock.

"Ride quiet - Ride Legally"

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Thanks for the pictures. That baffle is definitely different than what they were doing a few years back when I bought a Yoshimura. Back then, all they offered were end caps with 3 different diameter tubes about 2 inches long. To keep it quiet, you had to use the smallest tube, but it had a definite impact on power. I am glad to see that Yoshi has improved their product since then.

A note about decibels (dBs). The computation of dB's involves the use of logarithms. That is why they scale somewhat funny.

Earthquakes also use a logarithmic scale, the Richter scale. For earthquakes, every increase by 1, is an increase by 10 in magnitude. So, a 7.2 earthquake is ten times bigger than a 6.2. An increase of 1 on the Richter scale equates to an increase of 10 in magnitude.

For dBs, there is a multiplication by 10 tacked on. So a motorcycle producing 102 dB is ten times louder than one producing 92 dB. That is, you have to increase by ten in dBs to increase by ten in magnitude. An increase of 20 dB is an increase of 100 in magnitude. An increase of 30 dB is an increase of 1000 in magnitude. dB's are an engineering way of mapping large changes in magnitude to small changes in dB. My guess is that we will soon see politicians using dB's to express the federal deficit.

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I'm fully aware of the logarithmic scale. I'm a geo/hydrologist.

I think a problem with loud bikes, and that lots of people don't think they have loud bikes, is that they never stand behind their own bikes. They're always riding them, with a helmet on(hopefully), and don't really ever stand behind their bike where all the noise is being generated. That's where the bikes are loudest. When my bike blew a 102, I didn't think it was that loud (I'm guilty!!) but when I had it sound tested, I stood behind it, and damn, it was much louder than I thought earlier.

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