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My Akra CF muffler has a rattle :(

19K views 58 replies 23 participants last post by  Steve H 
#1 · (Edited)
Just coming back from a ride today and I began to hear some funky noise emanating from my muffler body area. Once home, I tapped on the body and heard a small rattle. My initial thought was the dB killer screw came out, so off came the muffler. The dB screw was still intact and the rattle was stronger when shaking the muffler while off the bike. All the rivets were tight on the outside. Hmmmm? It is under warranty and the Parts-Unlimited vendor is my bro-in-law, so no concerns there. Hoping I can just keep the muffler on and get the can replaced, but I have a feeling the whole exhaust will need to come off as a unit. I'll know more next week. Hope this video works..
 
#35 ·
It sounds bloody awful... and had anyone heard this (and have been told that it was quite normal) I'm sure that they wouldn't of sold a single unit. But the fact that, fortunately, most are not getting this is evidence itself that it's not right (or supposed to be there).

But Akra & their retailers are doing the right thing and replacing them so not a problem. I agree that it is odd that it disappears when the baffle is removed. I'm, errr.... baffled!

Steve
 
#37 ·
IMHO with the baffle removed the gases are more free flowing (i.e. less back pressure) which does in my experience reduce performance (possibly solved with a tune, but not always) but I think having less back pressure on the internals removed the rattles (as said, possibly erroneous frequencies). But have to say I don't recall hearing the noise when on the move?

But then who wants to rev their bike and have it sounding like a bag-of-spanners knocking around?

Steve
 
#39 ·
So guys - is this issue only on the Carbon version ? I'm shocked that Troop still had issues AFTER a new can was sent out ! I'm starting to lean towards the Titanium option ...
 
#40 ·
Chris... honestly, I'd go for the Termi system now had I the choice again. 1; it can be had a little cheaper on Ebay, 2; it comes in all black and 3; it sounds just as good!

If it comes back and still makes a noise I'm gonna re-pop rivet it myself then drill multiple holes in the baffle as I firmly believe it's the back pressure that's causing the rivets to rattle (when the baffles not in there's no rattle) so with less back pressure it may cure it, and give it a bit more bark!

Steve

Ps. Don't forget Two Bros make brilliant exhaust and the baffles come in and out with the greatest of ease!
 
#45 ·
Cheers Steve - Happy New Year !

Yeah i got a few options to weigh up. I can get Akraprovic at list price as my mate does a lot of dealings with the UK Importers so its still likely to be an Akra of some description ! I do like the Arrows too but they are expensive. For a decent sounding system (with baffle in!) its likely to be Akraprovic but i'll look the others up all the same.

Two Brothers looks good - Texoma wrapped his pipes - not sure if you can get them black but its a good looking system and sounds good too ...

http://www.fz09.org/forum/69-xsr900...thers-s1r-black-series-exhaust-installed.html

I'd have to pay full price on one of these tho !

Cheers,
Chris.
 
#41 ·
My Akra has never rattled. I've only run it with the baffle out. It does indeed make more power with the baffle removed.

This is not a widespread problem, as far as I can tell... with as many Akra systems that have been installed on this forum alone. Odd that even the replacement rattles.
 
#42 ·
Being the OP, and after having (2) cans with the same issue, I believe it is a frequency resonance sound versus a "rattle". With the dB killer installed, it is a sound only audible at low rpm/just off idle as the bike revs down. It is never audible while riding. With the dB killer removed, it is not audible at all anytime. I don't think this exhaust is even remotely loud with the dB killer removed, so that's how I ride it. I'll still likely play around a bit with the dB insert, starting by just adding a few extra holes to it. I still have a few months till riding time so not a priority...
 
#46 ·
Just as an update to my plight... my dealer sent the exhaust muffler away to the main UK importer who offered to make a repair to the rattle in the muffler and I agreed (as it is already ceramic coated) so they passed it to their tech team who replaced all the ss rivets but incredibly the rattle was still there! Wonders never cease uh!

They are now replacing the muffler, but even that doesn't guarantee a 'non-rattling' can!? But fingers crossed.

Although the main UK importer has acknowledged they've had a few back that rattle, I still can't get Akra to acknowledge it :-( they just keep firing my emails back to the UK importer even when I ask them explicitly to respond to me. Bit of a cop out I feel. Very disappointing. Glad I've got a good dealer though.

If the replacement rattles I'm gonna try cutting the baffle down 50% of the tube that's in the muffler and drilling holes in what's left, I don't really fancy riding without any baffle at all.

Steve
 
#47 ·
Hi Guys

Thought i'd update you on my exhaust issues. The replacement muffler also had a rattle which was pretty disappointing and as previously said I was about to try cutting the baffle down a few inches but decided to have the ECU tuned before I did that.

I sent the ecu to Wiz tuning (a UK company) a few days ago who did it for a fab price and got it back today. The guy there seemed to think the problem was the AIS pushing air into the exhaust that was causing the rattle. I had my reservations but since I was having the tune to smooth out and sharpen throttle response, etc... I also wanted the AIS switched off.

After fitting the ecu back in tonight I started the bike and the throttle immediately feels sharper and of course, all the popping has gone BUT the rattle has also gone!? Go figure!

Not been out on it yet, but will be soon enough! Can't wait to see how it handles now :)

Steve
 
#48 ·
Ah, good fix man, kudo's.

Steve 1 / Akra CF Can Rattle 0
 
#51 · (Edited)
Just a thought here. David flashed my ecu. At the same time I bought a new exhaust. I still had popping on decel. David (vcyclenut), he told me that when you disable the ais the rubber like plunger inside the engine that shuts off the air intake sometimes leaks so air still escapes out into the exhaust causing the popping.

That was my case, so I installed block off plates and popping was gone. Worked for me. Troop, do you have block off plates? Most don't install them after flash. Hell I wouldn't have if it wasn't for the popping.
 
#52 · (Edited)
I think the rattle is actually exhaust resonance due to the db killer being installed. Deflected exhaust gasses hit normally exiting gases and the resultant opposite colliding waves cause a rattle like sound...although I have just drunk some beer and may be talking out of my arse....Mine makes a similar noise....I decided the people behind me can put up with it and I dont care
 
#53 ·
I think you're probably quite right, albeit an educated guess. There's definitely something a miss & if it comes back I will definitely be cutting down my baffle in length like the Two Bros baffles (tips) in the pic below. I'd wager that the Akra baffle is too long and penetrated too deeply into the muffler and the air pressure around the baffle is pushed back down the muffler until it's forced out (possibly in a cyclical motion)? But removing the penetration of the baffle (but retaining the top part) will increase sound slightly (no bad thing) and hopefully remove the effing nightmare that Akrapovic have created.

Oddly, I do not hear any rattled or unwanted noises when riding the bike, at any speed so am surprised you do.

Thanks for input guys, we will get to the bottom of this!!
 

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#54 ·
My Akra Carbon has a slight rattle as well and I run with the DB killer out. It's so loud I seldom if ever hear the rattle. Only time it is noticeable is when riding directly to the right of a barrier or wall. In all honestly, I screwed up when installing the exhaust and the bolt directly under the system is out but all others are tight so that could be it. Either way, it is very hard to notice and doesn't appear to affect performance.
 
#58 ·
I'm curious, is there anyone reading this thread (or that is reading this thread and knows somebody who has this bike and exhaust combo) that doesn't have this issue? I can't honestly believe Akrapovic built this exhaust system and didn't test it thoroughly with many many hours of use)?
 
#59 ·
Any rattle when the muffler is off the bike will be from left over internal debris from riveting the whole thing together...IMO. The debris will be very difficult to remove due to the internal baffle material, which is held in place against the muffler outer by mesh...I cant see Acrapovic assembly line workers spending any time shaking them to try and remove it.
 
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