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I have loud pipes on my 907 now and I found the original factory pipes on Ebay and bought them cheap.Can I just put them on without any jetting or changes.Thanks...

macwig wrote:I have loud pipes on my 907 now and I found the original factory pipes on Ebay and bought them cheap.Can I just put them on without any jetting or changes.Thanks...

macwig,

Probably not. Aftermarket cans are usually, (but not always!), installed with a dedicated EPROM chip that changes EFI parameters so that the engine runs properly with the free-flowing exhaust. If your 907 has an exhaust chip in it along with your exhuast cans, (and if it doesn't, you'd know it, 'cause your bike would be running like crap!), then just re-installing the original exhaust without the original chip will cause your 907 to run rough and/or not idle properly. You need to find an original chip.

But why? The aftermarket cans provide more horsepower and allow the 907 to develop its full potential. The factory exhaust is too restrictive. Are your cans that much louder than the OEM exhaust?

Elton

mrinflux wrote:

macwig wrote:The aftermarket cans provide more horsepower

No, aftermarket cans dont make any more power, but that CHIP (to added to them) makes that "more power", if its suitable and bikes injection system is tuned well.... Power comes from MORE fuel(and surely more air), better flow characters(engine "breathing").... Its little funny, that aftermarket exhaust sellers tell often, that you can get more power with they pipes I have talked with this thing many times with guys, who tune and race with Ducatis here, so i have "learned" something....

so why do guys race with 50 or 60mm headers and open exhausts ? Motorcycle races would be way less noisy if they would use the original exhausts instead
I guess the correct way would be to say that aftermarket cans can provide more horsepower.
I`ve seen tests of aftermarket exhausts compared to an original exhaust on a stock bike and actually numerous aftermarket cans were worse than the original. They made more noise than the original but often produced less power.
Things change (depending on the aftermarket exhaust system used) if the engine is modified and/or setup correctly to the exhaust (ie so it doesn`t run lean). The additional power will come if the combinations of all modifications is correct. This takes a lot of experience and knowledge. that I unluckily don`t have

G.

Finnpaso wrote:No, aftermarket cans dont make any more power, but that CHIP (to added to them) makes that "more power", if its suitable and bikes injection system is tuned well.... Power comes from MORE fuel(and surely more air), better flow characters(engine "breathing").... Its little funny, that aftermarket exhaust sellers tell often, that you can get more power with they pipes.

Finn,

As you pointed out, burning more fuel and better flow characteristics generate more power. "Flow characteristics," are greatly affected by exhaust design. You can't get more fuel into the compression chamber than you can get out. A less restrictive exhasut system allows more exhaust gases to leave the compression chamber quicker. While back pressure is important, (especially for lower rpm power), generally speaking, the less restrictive an exhaust system is, the better the engine aspirates, and increased aspiration means more horsepower.

Finn, I've read enough of your posts to know that you like to argue just for the sake of arguing. So if you want to believe that exhaust designs, (and in particular, aftermarket cans), don't have any impact on how an engine breathes, then go ahead; I couldn't care less. Shove rags into the end of your tail pipes for all I care. But you'll have to drag somebody else into this moronic debate. The fact that exhaust design affects engine aspiration is so obviously true that I'm not going to waste my time trying to persuade you. If you want to live in denial, be my guest.

Peace, Elton

Guys, go slow.
Although Antti likes to be provocative sometimes i think we can agree that it`s often a matter of misunderstanding and of guys discussing who`s mothertongue is not english which includes me, too.
I would agree with you both. An aftermarket exhaust alone (with no other tweak) will change very little to nothing. The engine may aspirate better but it will not produce more horsepower. Actually it will run lean (still speaking of an original untouched bike). If you then reprogram the Eeprom to match the exhaust you will get more fuel in the compression chamber. That is when you will get more power.
If you two disagree to this little summary, continue to bash your heads - I`m outta here

mrinflux wrote:An aftermarket exhaust alone (with no other tweak) will change very little to nothing. The engine may aspirate better but it will not produce more horsepower. Actually it will run lean (still speaking of an original untouched bike). If you then reprogram the Eeprom to match the exhaust you will get more fuel in the compression chamber. That is when you will get more power.

That's the truth, so it's also true (according with the magazines I read) that sometimes the aftermarket cans get less power than the stock ones.
So, the whole engine has to be very well balanced to get the best performances.
Peace & love .
Ciao

paso750 wrote: An aftermarket exhaust alone (with no other tweak) will change very little to nothing.

I agree 100%

paso750 wrote:The engine may aspirate better but it will not produce more horsepower. Actually it will run lean (still speaking of an original untouched bike).

I agree 100% again...

paso750 wrote:If you then reprogram the Eeprom to match the exhaust you will get more fuel in the compression chamber. That is when you will get more power.

I agree 100% again , maybe i would say, that i agree this "200%"

paso750 wrote: Although Antti likes to be provocative sometimes

Ok, I have seen, that "everybody" dont like my style, as its very "straight and open", no matter my english is very poor compared to my home language. I really dont care of it at all... btw about "provocation": I do it very rarely, near not at all... As this is open forum, i can write to here... Its not MY problem, if SOMEONE "dont like my style".... Anyway i am Paso ENTHUSIASTIC..... STILL !!!! And i really dont want to hurt anybody, as i am very peacefull person !

Guys guys guys,tsk,tsk,tsk. Changing the exhaust on any fuel injected engine without remapping the eprom will
1 make more noise
2 make the engine produce less power
Changing the exhaust and remapping the eprom alone will
1 make more noise
2 make the engine produce less power
There is nothing to discuss or anything worth arguing about. It is a simple proven fact. Period
Now if you change the exhaust with a corresponding change to the intake airflow and the proper remapping of the eprom it is possible to wring out a little bit more power. a few ponies more
Adding more fuel will just make your engine run richer.
Internal combustion engines run on air.
to get more power you have to get more air into the engine or compress the air more. That's it there is no other way.( well almost no other way,there is always accelerants like oxygen)
Fuel is simple the agent used to heat the air. Fuel will only heat the air properly at 14.7 to one That is 14.7 units of air to one unit of gasoline by mass.
Generally it will take more than remapping and Exhaust and intake mods to get a real increase in power. Cam timing needs to be considered to get real improvements and most of those kind of improvements require higher rpm, but raising compression is still the best way to go. ADD CUBES OR ADD PRESSURE. or

Macwig, you have just as good a chance as not to find the stock exhaust will make your 907 run better,the only way to find out is put it on, anything else is bullshit If you put it on and it runs worse,then the controller has been remapped and you will have to find a way to deal with it. Throw in if your airbox has been modified and it could get complicated
Let us know what and how you make out, Even Antti will be interested to know

Ahhhrrr come on guys don't back down just now I was really looking forward to a Duel at Dawn with your Eprom chips in one hand and Exhausts in the other.

United Nations here we come.

I read this topic queit and quick.
this must be the first time that the guys who react make more noise than theyre exhausts
But still: no power or torq
if you want to change the cans for a more open type you HAVE to consider the whole sytem otherwise you produce just more music. In case of any Paso I don't talk of noise

ducbertus

This thread seems like fun.

Changing the exhaust and remapping the eprom alone will
1 make more noise
2 make the engine produce less power 1
There is nothing to discuss or anything worth arguing about. It is a simple proven fact. Period
Now if you change the exhaust with a corresponding change to the intake airflow and the proper remapping of the eprom it is possible to wring out a little bit more power. a few ponies more
Adding more fuel will just make your engine run richer.
Internal combustion engines run on air.
to get more power you have to get more air into the engine or compress the air more. That's it there is no other way.( well almost no other way,there is always accelerants like oxygen)
Fuel is simple the agent used to heat the air. Fuel will only heat the air properly at 14.7 2 to one That is 14.7 units of air to one unit of gasoline by mass.
Generally it will take more than remapping and Exhaust and intake mods to get a real increase in power. 3 Cam timing needs to be considered to get real improvements and most of those kind of improvements require higher rpm, but raising compression is still the best way to go.

My remarks w bigger letters.

1. Bikes are usually on the lean side from factory. Carbed bikes usually get a one size bigger main jet w open cans = giving a little more power.

2. Most power is generated w a A/F of 12,5-13. 14,7 is the ideal chemical (stoicmetric) burn.

3. Open exhaust & open airbox/similar + fuel improvement gives like 3-5 Hp on a Duc 2V 900.