Akra Carbon - Don't Like It

[kylerhsm]

Hi guys.

 

Purchased an MT-07 yesterday, absolutely love the bike overall, but am really dissapointed with the sound of the Akra Carbon with baffle. It sounds great at idle and light throttle, but in my opinion sounds nasty once you open it up. It loses all its bass and makes loud noise and that's it, kind of like air popping/spitting and as if the muffler has lost its ability to muffle the sound. Now there's nothing wrong with it, and it sounds just like others on Youtube etc. but I was hoping that in person it would be different.

 

My question is, is there anything I can do to add additional muffling to the setup? I've thought about installing an inline catalytic converter to perhaps break up the sound wave a bit. I've seen them on Akra's website and also inline ones on eBay but not sure if they can be retrofit to the Carbon. The other option would be to ditch the end can entirely and add a larger muffler to the Akra carbon headers.

 

Why did I get the Carbon? It came with the bike. I'd have prefferred the Titanium (loved it on my XSR900) but there wasn't a good deal locally.

[kylerhsm]

I had some time to play around on the weekend and do some sound tests. I did 3 tests, at a standstill in neutral only so not whilst riding.

 

1. Akra Carbon + db killer - Sounds OK at idle, but as per my previous comments and observations while riding, once you rev it up it sounds quite high pitched and unpleasant. It loses the bass tone and gives the impression that the air is being forced out a too small hole.

 

2. Akra Carbon - db killer - Sounds great at idle. Deeper than with the db killer. Sounds quite nice when you rev it up and maintains the bass tone, although at a noticably higher volume. Man this muffler is light! On the road to work this morning, man it sounds really good, but just way too loud. It's deep and maintains a very nice tone throughout the rev range, but with way too much overall volume. Not an acceptable solution for me.

 

3. Mivv Suono (no db killer) from my R3 mounted (just taped temporarily until the pipe reducer I ordered arrives). This muffler has a 44mm inlet and the same size outlet as the Akra Carbon. It's also slightly bigger, and noticably heavier. To mount it properly, I'll need the 2" to 1.75" reducer. This sounded more like the Akra no db killer, but also quieter. It's also a far nice looking muffler. I'm hoping that once I get the reducer and can properly road test it, that it will give me the sound I want. I'm assuming that the 2" to 1.75" reduction before the muffler will help with both reducing the overall noise and minimising some of the popping/backfiring caused by the Akra with no tune. I also have a db killer for this pipe which I'll be able to test as well.

 

Lastly, I have also ordered in inline cat/db killer off eBay which sits within a 2" pipe and has the honeycomb mesh grid you get from a cat. This may be an option combined with the Akra Carbon as it should be able to be mounted between the muffler and the header (at the muffler inlet side). I'm hoping that this may work as an overall volume reducer and might break up or disperse the sound wave that booms along the header. I'll test this option when it arrives with each of the 3 items above.

 

My overall goal is to retain the sound of the Akra Carbon with no db killer, but also reduce the volume. That or run the Mivv. More updates to come once I get the new parts.

[shinyribs]

Might look at how the DB killer is constructed for clues. My baffle in my Arrow had a slight puffy sound at idle and I noticed that all of the holes in the baffle were around the perimeter of the baffle. I drilled a hole in the center of the baffle so that all the exhaust gases didn't have to make a hard 90° turn to get out the muffler and the puffy sound went away all but at a couple spots in the rev range. The sound volume didn't really increase, so I popped a few more holes until the puffiness cleared up and only gained a noticeable amount of extra volume. Still quiet enough to not attract any unwanted attention.