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Discussion Starter #1 (Edited)
Hi guys and gals,

Ok recently I was moving some stuff at home and came across my old db killer/baffle from my Musarri slip on. Looked about the same diameter as the one I have in my full Yoshi system I thought to myself, wonder if it would make any difference to dB levels or tone/note if I were to whack this one in compared to the one that Yoshi gives you, which essentially kills nothing.

So I did and it changed the level dramatically. Of course I had a very very slight loss in top end due to the added backpressure, but if anything has shifted the power/torque curves lower down in the range than previous. But that wasnt the aim of the exercise, it was to see if I could make the exhaust a little quieter, to increase my enjoyment in riding the bike and for the sanity of others around me. And much to my surprise, it worked much better than I ever expected it to. Firstly some pics of the smaller baffle.

So the smaller baffle installed looks like this:



Now of course being a baffle/dB killer from a slip on and not a full system, the opening for the exit of the exhaust is smaller as you can see, and the amount of flow of gases through the perforated pipe that is attached is not sufficient. And it was 2mm smaller in diameter than the Yoshi baffle so it didnt quite seal properly. But after going for a ride, which was quite a longish one, I really enjoyed the tone and reduction in sound.

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So it got me looking more closely at the Yoshi baffle and how to go about modifiying this one, to allow more flow of exhaust gas, but at the same time reducing and diffusing the flow for a reduced dB level. So here is what I have done, and how to go about it for those that wish to reduce the dB level of their exhaust systems a little. This modification can be done to pretty much any baffle/dB killer for any exhaust, regardless of full system or slip on.


Firstly take the original baffle:




The Yoshi baffle has a collar on top that simply pulls off like this:


If the collar didnt pull off, I was simply gonna cut the pipe on the Yoshi one and replace with the new pipe. But this came off so I was able to eliminate having to cut and weld this pipe. Bonus. You want to use the original mounting collar as it is already the right diameter to fit your pipe and seals well.

The replacement pipe I bought for this mod was a 1 & 1/2 inch diameter louvered pipe, 5 inches in length. The reason I got some louvered pipe instead of perforated, one it was all I could get hold of and two it flows better than perforated due to the design. Air naturally flows through the louvres compared to being forced through perforated.....but either will suffice. You guys in the US will be able to find this stuff easy, every shop I looked at to buy some from was US based.

The new pipe I obtained looks as such:




As you can see in the photo, I had to slightly file the top part of the pipe where it slips in to the collar, this was pretty rough when I got it and slightly too large and tight to go in smoothly. 5 minutes of hand filing later, slipped on perfectly.

With collar attached to new pipe:



Now as I mentioned earlier, if your baffle doesnt have a collar, you can simply cut off the old pipe and weld on the new pipe. But of course you would need access to a welder and the skills to do so, but if not a local fab shop in your area shouldnt charge you much more than about 10 bucks to do this its a quick 5 minute job. Any place that does any type of welding can do this, easy as pie. Or a carton of beer for a mate with a welder...........

So now looking down end of baffle:



Now you will need to drill a hole to accept the new fixing bolt. I simply drilled it with the Yoshi collar in place, as it helped me to locate properly and not wander on the pipe. Plus it doesnt matter if your drillbit hits the inside of the hole on the collar, you never see this when mounted.

Pipe with new hole drilled, I used a 6.5mm drillbit:



And with collar removed:



Now you will need to find yourself a bolt to use to fix to the muffler. You can use the one that came out from previous if you wish, be sure it will fit though and is the right length. Mine was holding in the smaller baffle so I sourced a new one.

The bolt I bought was a M6x12 socket head type such as these:



But any size that will work for your application is fine, just be sure it is able to be screwed into the nut on the inside of the pipe.

Which brings me to the nut. This will need to be tack welded on the inside of the pipe aligned with your newly drilled hole to accept the bolt. What I did was remove the collar, put the bolt through the hole and tightened the nut on the inside of the pipe. I then placed a small tack weld on the nut on the inside of the pipe to hold it in place. I did this tack weld whilst the bolt was done up tight, again to properly locate and to ensure correct alignment. Once this is done you can remove the bolt and slide the collar back on.

I will continue this in two parts, I have reached my attachment limit and am still in the process of completion.

Stay tuned for part two.
 

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Discussion Starter #2 (Edited)
OK Part 2.

This is what you should now have after welding the nut on the inside of the pipe:



Excuse my shitty tack welds, forgot to alter machine settings before having a crack. That and I havent done any welding for about a year or so now :eek:

Next is to cap the end of the pipe like so:



You dont have to cap the end if you dont wish, you may be able to get around having to do any welding at all if you choose not to cap the end, and jbweld or something similar that sets hard could be used to set the nut in place on the inside of the pipe. If I didnt have access to a welder this is what I would have done.

Now remove the bolt from the pipe and slip the collar back on. Re-install bolt so as not to lose the tiny little thing.

With collar installed:




You now have a finished quiet baffle ready to be installed back in the muffler!!! First off I will be painting this pipe with some high temp flat black so as to get rid of the horrible bare metal finish if you ever happen to look down the end of the muffler. This isnt needed as it will blacken with use anyway from soot, but for a self confessed OCD person like myself.........just not good enough.

So essentially, all I have done is replace pipe with louvered/perforated pipe, drilled new fixing hole in pipe, fixed nut on inside of pipe and capped the end. Voila!!!!!!

Hopefully with this installed, there will be no loss in any feelable power or torque, but a significant reduction in exhaust dB and tone. I think there is enough flow that it wont be restrictive, yet enough areas of diffusion to alter sound levels.

Will post a pic when I get home of the finished painted baffle and also when it has been installed in the muffler. Will see about getting a video for comparison for yall, but we all know how shitty they sound on video and how they do not reflect the actual sound at all, so will see. Plus that means I have to put on and take off the muffler another 2 times just for a comparison video, fuck that.

Will see kiddies, will see. :cool:
 

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Discussion Starter #4
Cheers. I thought I would have a crack, not a huge fan of the overly loud exhausts.......but knew what I was getting into when I bought the full system so cant complain.

By the way for those reading also, these types of baffles/dB killers can also be bought on ebay relatively cheap. Find the right diameter and length that you are after and away you go. Most of these sorts of baffles are for the cruisers and harley's, to quieten those down. So if it makes those obnoxiously loud exhaust systems quieter, thought I would give the same design a crack on the 300.

Will let you know how I go maybe tonight, maybe this weekend. We got a bit of weather coming through at the moment. I expect quite a reduction in dB if the smaller baffle that I put the other day in is anything to go by. Has totally lost that annoying "in your eardrum" vibration/tone that these types of exhausts get at the higher revs.
 

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Discussion Starter #6
Thanks mate.

I figured since I work in a fab shop, might as well actually try and fab something......... :rolleyes: Been a while though thats for sure. My little office boy hands just arent used to that sort of abuse anymore!!!!
 

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Discussion Starter #7
Painted last night with some heat proof flat black engine enamel, just to prevent or inhibit any rust from forming and also to help it blend in so you dont really see it inside the muffler. Ready to go back in, lost light pretty rapidly yesterday arvo so will chuck it in this weekend and test for sound.



 

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This is the second post I've seen recently regarding slip-ons being too loud. Are they all too loud or is there a brand out there that only increases the dbs slightly? I too don't want to be too loud, just a little louder than stock?
 

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I was just looking at an exhaust that had what looked like this but on the inlet of the muffler rather than the outlet. Now I wish I could remember who that was... There was also an outlet doohickey too.
 

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This is the second post I've seen recently regarding slip-ons being too loud. Are they all too loud or is there a brand out there that only increases the dbs slightly? I too don't want to be too loud, just a little louder than stock?

just about any aftermarket exhaust you can buy a silencer / db killer for it from the manufacturer
 

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They sell baffles on ebay pretty cheap. I have one for my M-4 exhaust. I need to drill a hold to attach it though so I havent put it on yet.
 

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Discussion Starter #16
Yep most baffle sizes you can get on ebay, I was actually gonna buy a 1 & 1/2 baffle from there, but as the Yoshi one sealed real nice I just used the collar/mounting ring from that.

Plus the baffle to buy was less than 10 bucks, but as they were all in the US the shipping was twice the price of the baffle at over 20 bucks. So it turned a 10 dollar baffle into a 30 dollar baffle, stuff that. So I tried my hand at making one, and it turned out pretty bloody sweet I reckon.

Will be installing tonight or tomorrow when the weather clears up a bit, the Ninja is under a cover at the moment so the sky doesnt piss on her.

dkw12002 said:
This is the second post I've seen recently regarding slip-ons being too loud. Are they all too loud or is there a brand out there that only increases the dbs slightly? I too don't want to be too loud, just a little louder than stock?
From what I have heard, the Akrapovic is probably the closest to stock dB than all others. 2Bros, M4, Yoshi, all super ghetto loud especially with the dB killers out. The quiet core from Area-P also sounds very nice, but is only available as a full system and IMO they dont look as nice as others.
 

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Scorpion with the baffle in is relatively quiet. According to their site, it's barely above the sound level of the stock exhaust. It also doesn't need repacking so it won't get louder over time.
 

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That's exactly what I wanted to hear tfk. That's probably the slip on I will get. My neighbor has a 250 with an aftermarket slip on that is very noisy, plus on a 250 it looks like he is running in slow motion with the big bike sound but little bike perfomance. Something just a bit louder is what I want and sounds like the a Yoshi with the baffle is the way I'll go. Good info.
 

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Jeff, do you have a vid with the sound of this modified baffle? I love the sound of Brans without the baffle but I saw a bike cop on the bridge on Mortimer Road lasering the freeway and am worried they pick me up for it being too loud (when I do get it). She says it makes a more deeper sound but not louder. The sound her bike makes it exactly what I want TBH. Does this baffle make a deeper sound close to it?
 
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