Akrapovic Baffle in/out

Thorium · Jul 22, 2008

Yesterday curiosity got the better of me, and I decided to see what happened if I removed the baffle in my Akrapovic can. A bit more detail:

Configuration: 2008 R1200GSA, original headers, Akra can supplied by BMW. Only 900 miles on the bike.

Objective: See what difference it would make to engine torque, and see what would happen to severe vibrations I am experiencing from 4000-5000 RPM.

Seat-of-the-pants dyno results:
Low end torque (1500-2500RPM) noticeably worse.
Low-to-mid torque (2500-4000) no noticable difference
mid-to-high torque (4000+) no difference, and still vibrates like crazy.
Idle: Pretty bad.
Sound: My neighbours decided to move further out in the countryside.

So in the end, a more open exhaust yielded no improvement (at least for me), quite the contrary. I envision that I need more back pressure to maintain or increase low-end torque. I am really looking for torque and smoothness, without sacrificing fuel consumption.

Does anybody have dyno readings on the BMW Akra with or without baffle? (I assume not, as it is not a widely used configuration).

Comments are welcome. :moped:

TM

alimey4u2 · Jul 22, 2008

When I first bought my bike the dealer said: "It will run on any gas in the world, needs about 1/2 hour of riding to get the parameters sorted". This may well have been utter salesmanship b@llox but if correct, I wonder if that would also apply to exhaust changes.... :nenau

red1 · Jul 22, 2008

Removing the baffle out an exhaust in most cases will not give any increase in power.

The system is designed to create pulses (just like a 2-stroke) which sort of creates a sucking action to pull the gases out of the engine. Part of the design of the can is to create back-pressure to aid those pulses. Take out the baffle, which is there to help with the back-pressure, and it breaks up the flow and gives a decrease in power in most cases as the gases slow down.

Even changing the length of the header pipes can have a significant effect on power. That's why the best result you get with aftermarket cans is a more pleasing sound.
Even the best designed can will not give more than 1-2% power increase at best, which on a GS relates to 1-2 BHP increase. Some of the better cans can give slight inceases in torque, but 99% of riders will never notice the change.
But it will sound faster!! ... and of course some colours are faster than others!!

faantjie · Jul 22, 2008

The only reason I remove mine is to aid driver awareness of motorcyclists and spoil driver phone conversations whilst driving with an open window....or not.... :augie

robb · Jul 23, 2008

Thorium said:
Yesterday curiosity got the better of me, and I decided to see what happened if I removed the baffle in my Akrapovic can. A bit more detail:

Configuration: 2008 R1200GSA, original headers, Akra can supplied by BMW. Only 900 miles on the bike.

Objective: See what difference it would make to engine torque, and see what would happen to severe vibrations I am experiencing from 4000-5000 RPM.

Seat-of-the-pants dyno results:
Low end torque (1500-2500RPM) noticeably worse.
Low-to-mid torque (2500-4000) no noticable difference
mid-to-high torque (4000+) no difference, and still vibrates like crazy.
Idle: Pretty bad.
Sound: My neighbours decided to move further out in the countryside.

So in the end, a more open exhaust yielded no improvement (at least for me), quite the contrary. I envision that I need more back pressure to maintain or increase low-end torque. I am really looking for torque and smoothness, without sacrificing fuel consumption.

Does anybody have dyno readings on the BMW Akra with or without baffle? (I assume not, as it is not a widely used configuration).

Comments are welcome.

TM

Leave the baffle in and get some remus headers :thumb2

That'll tick most of the boxes above.

Mine doesn't run very smoothly with the baffle out and there is no noticeable power increase either. IMHO Power gain is all from the headers and ditching the cat.

(I have remus headers + BM Akro can)

SiMo · Jul 23, 2008

I also have a dealer-fitted Akra on my 2008 GS. Sounds much much nicer (baffle in) than the original, looks better too. Baffle out increases the noise, but in my view not in a pleasant way. Keep the baffle in! I think Remus headers is the way to go (next on the list...)

faantjie · Jul 23, 2008

A bit off the topic but still performance related. I was "advised" to change to a performance filter after mentioning that there is a bit of a flat spot when accellerating. I've not fitted the filter yet but I'm keen to see feel the difference if any.
Soooo....Remus headers, Akro pipe and a HP filter will gain you how many extra donkey power for a few bob short of £900. :nenau

All I need now is the Remus header........ :augie

red1 · Jul 24, 2008

faantjie said:
Soooo....Remus headers, Akro pipe and a HP filter will gain you how many extra donkey power for a few bob short of £900.

As a tightwad tosser that's always been my problem ... £900 for 2-3bhp that I'll probably never know is there and never get to use anyway.

Thorium · Jul 24, 2008

red1 said:
As a tightwad tosser that's always been my problem ... £900 for 2-3bhp that I'll probably never know is there and never get to use anyway.

Thanks,
I did realize that the result wouldn't necessarily be an improvement, but I was surprised by how much worse the engine actually performed with the baffle out. I guess a lot of people would gladly throw a few ponies away for the joy of pissing off their neighbours, but not this guy...

It was a fun experiment, though.

fekker · Jul 25, 2008

I love this site. There I was thinking to meself... I'm going home, having a quick tea, then gonna jump on the bike and zip up to Norfolk to take the evening air...and I know, I'll whip out the Akro baffles to see what happens...and here's the answer. I LOVE YOU ALL...more riding time and the contented thwomp of an Akro below...
or is it a phthwoump...
Thanks guys!

Thorium · Jul 27, 2008

fekker said:
I love this site. There I was thinking to meself... I'm going home, having a quick tea, then gonna jump on the bike and zip up to Norfolk to take the evening air...and I know, I'll whip out the Akro baffles to see what happens...and here's the answer. I LOVE YOU ALL...more riding time and the contented thwomp of an Akro below...
or is it a phthwoump...
Thanks guys!

Glad to hear that I saved you a couple of minutes. That being said, it is extremely quick to pull the Akra baffle out if you want to try, at least mine, as it has no welds, just the single screw. If you get a different result than mine, let me hear about it.

There are plenty of unsubstantiated claims about the benefits of baffle removal, because it "sounds faster." Apparently sound travels faster than bad news...

Arsey · Jul 28, 2008

robb said:
Leave the baffle in and get some remus headers
That'll tick most of the boxes above.

Mine doesn't run very smoothly with the baffle out and there is no noticeable power increase either. IMHO Power gain is all from the headers and ditching the cat.

(I have remus headers + BM Akro can)

+1

Akrapovic Baffle in/out

Thorium

Registered user

alimey4u2

Registered user

red1

Well-known member

faantjie

Registered user

robb

Registered user

SiMo

Registered user

faantjie

Registered user

red1

Well-known member

Thorium

Registered user

fekker

Registered user

Thorium

Registered user

Arsey

I identify as a Donkey. My pronouns are He/Haw

Similar threads