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I have bough the Blackbird with the 4-1 system installed, but it is actually annoyingly noisy - especially for the rider ! I have tow questions - is there a simple way of adding more padding inside the slip-on to reduce some noise ? Secondly what would the power loss be should I decide to put the original exhausts back on ? Anyone with experience with this ??? Thanks 馃槆
 

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There are no packing kits from Akrapovic that I've seen, not that it can't be done with other exhaust packing, but you'd have to drill out the rivets to get at it. You'll lose several hp and gain about 20 lbs. You haven't mentioned if it's carb or f.i., carb bike will need rejetting back to stock and there is hopefully a Power Commander on it if it's f.i, which should have a map installed for the pipe.
Make sure it's just not leaking past any gaskets first or where the head pipe meets the elbow.
 

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Agree with partguy, install new packing (it wears out over time) although I believe it weighs about 2lb not 20. Also, google "db killer motorcycle exhaust" for various pieces that can help cut more noise (only slightly effective IMO). I went thru this and ended up putting stock units back on for the sake of the neighborhood and my hearing.
 

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I have bough the Blackbird with the 4-1 system installed, but it is actually annoyingly noisy - especially for the rider ! I have tow questions - is there a simple way of adding more padding inside the slip-on to reduce some noise ?
Well, I took my Akrapovic apart to powdercoat it. And I can tell you the packing inside is really maxed out tight! No way you could add to it unless it's worne/burnt then you can ADD or replace with any high quality exhaust packing. However, a 4 into 1 sound is a 4 into 1 sound! Which as you know differs from 4 into 2 sound(And the lost of a couple HP's and added weight). In fact I removed the packing for some extra kick and extra noise! Never been stopped! Knock on wood! :sneaky:
 

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Discussion Starter #11
There are no packing kits from Akrapovic that I've seen, not that it can't be done with other exhaust packing, but you'd have to drill out the rivets to get at it. You'll lose several hp and gain about 20 lbs. You haven't mentioned if it's carb or f.i., carb bike will need rejetting back to stock and there is hopefully a Power Commander on it if it's f.i, which should have a map installed for the pipe.
Make sure it's just not leaking past any gaskets first or where the head pipe meets the elbow.
Thanks :)
 

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Discussion Starter #12
Agree with partguy, install new packing (it wears out over time) although I believe it weighs about 2lb not 20. Also, google "db killer motorcycle exhaust" for various pieces that can help cut more noise (only slightly effective IMO). I went thru this and ended up putting stock units back on for the sake of the neighborhood and my hearing.
Agree !!!
 

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Just get an exhaust shop to manufacture a bolt in "db" killer which is basically just something to reduce the exit hole size. There is a little bit of science behind it i.e. length and diameter but an easy job. Just enough to take the edge off the sound.
 

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And depending on where and how you ride, you may not notice any drop in power going from a 4-1 to std. You MAY even get more power where you sit the most i.e. mid-range hp/torque
 

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It all depends on where the header is designed to peak it's scavenge effect. Pipe diameter, length, cylinder pairing and collector length all effect this point. The early BB headers were paired and designed to peak at a high rpm. The FI's at a lower point to enhance torque. The biggest advantage an aftermarket gives is weight reduction. To get the maximum benefit you need to match the pipe to where you want your peak and then tune to that point. All headers will be better than a cast iron log manifold. Gains from one header design to the next will most likely only be a few HP. The biggest difference will be where it comes on.
 

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The packing has probably been burned away from a few years of use, so repacking will help a lot....... has your muffler got a 'dB killer' in the tail cone?

If it's fully open it will still be loud even with new packing (just not ear splitting loud) ...... so you may still need a 'dB killer' tube to effectively reduce noise to acceptable levels for good neighborhood relations. It could be a spare part if you know the brand of the muffler..... or you can buy accessory dB killers on line if you measure the pipe diameter........ go for the open tube type, not the holy cone type (and they can be shortened to dial up the music to suit your preference).

Original mufflers weigh a tonne and if they are the cat type (eg like on my 05BB) with the fatter front tube near the collector clamp, they eat quite a lot of hp. The earlier FI and carby models had no cats (thinner tube to the big fat cans) and had a lot more power. But the Bird makes plenty so it was no big deal anyway.

Depending on the brand of the 4-1 you have, it may not make any more power than a standard exhaust anyway..... it might just sound better, or have a bit more grunt in the mid revs, or if it's a cheap system, it may even have less power than a stock exhaust...... but if it's a well designed system and has a Power Commander/ dyno tune up, it could have +20hp over stock at peak rpms. It will be very light so that is a huge advantage on our porky 260kg BB's.

You may get better fuel range with standard pipes (but if you have a carby model it may need re-tuning)...... but they are nearly silent - that's not all bad, I still have stock pipes on my FI BB after 15 yrs........:D - they just don't rust so I've never been forced to look at some slip-ons..... :LOL:...... and I like 420kms fuel range on tour in our lonely 'outback'.

(y)
 

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Discussion Starter #17
Agree !!!
I have located an exhaust shop close by that can redo the packing/cladding while I wait, probably an hours job. One drills out the pop rivets at the base, remove the cannister, redo the cladding and refit. Sound really easy if you have the extra hand to help ! :):)
 

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Repacked mine couple years back. 2 brothers sells a kit with the glass matting. What they don't sell is the steel wool inner core. But I just used bulk steel wool pads for furniture refinishing. Did a double wrap of it then finished off the rest with the glass. Have to have the steel next to the core or it'll just burn it out.
 
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