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Old 01-09-2013, 05:55 AM   #16
roger 04 rt
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Originally Posted by Marki_GSA View Post
The GS range to my knowledge doesn't have a MAP/barometric sensor. If it does it is very well hidden and doesn't show on the GS911 software. When I get time/weather I will do a back to back run with a wide band sensors and post the logs. Don't get me wrong, I am not saying your in the realm of engine damage. You can quite easily find yourself with less than optimal running though. Usually quite the opposite from what you wanted from tuning options.
As I mentioned a couple posts ago, all R series motorcycles have a barometric sensor buried in the ECU and the GS-911 does report it, see the data from an R1150 below. Ambient air pressure is column F.

It's my opinion that changing the exhaust or intake changes the tuning dynamically of the air flow based on what I've read in numerous books. When an exhaust pulse leaves the engine a pocket of high pressure air leaves the cylinder when it hits a change in exhaust geometry (e.g. wider or narrower pipe, the catalytic converter, etc.) some of that pocket of air reflects and travels back to the exhaust valve, we're talking thousandths of a second here. If the reflected pulses pressure is high while the exhaust valve is still open, less air fills the cylinder when the intake opens. If the pressure from the reflectednpulse is low at that moment, more air goes in when the intake valve opens. These dynamic conditions change with RPM. When you put on an aftermarket exhaust or intake you may change these dynamics which BMW has carefully measured and accounted for the the VE (volumetric efficiency) also know as the Fuel table.

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Old 01-09-2013, 09:55 AM   #17
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Originally Posted by roger 04 rt View Post
As I mentioned a couple posts ago, all R series motorcycles have a barometric sensor buried in the ECU and the GS-911 does report it, see the data from an R1150 below. Ambient air pressure is column F.

It's my opinion that changing the exhaust or intake changes the tuning dynamically of the air flow based on what I've read in numerous books. When an exhaust pulse leaves the engine a pocket of high pressure air leaves the cylinder when it hits a change in exhaust geometry (e.g. wider or narrower pipe, the catalytic converter, etc.) some of that pocket of air reflects and travels back to the exhaust valve, we're talking thousandths of a second here. If the reflected pulses pressure is high while the exhaust valve is still open, less air fills the cylinder when the intake opens. If the pressure from the reflectednpulse is low at that moment, more air goes in when the intake valve opens. These dynamic conditions change with RPM. When you put on an aftermarket exhaust or intake you may change these dynamics which BMW has carefully measured and accounted for the the VE (volumetric efficiency) also know as the Fuel table.

Very cool and yes I was sure that the ECU had those functions (especially in the newer models of R bikes) From my experience the comments you make about "pulse' etc. is correct and most times are accommodated but are most important in very highly tuned engines. Most specifically in engines that take advantage of megaphone exhausts - when building a cam or engine timing in conjunction with the properly calculated taper and exhaust length & carb intake length one can in effect use the shock wave/pulse to hold gasses in the cylinder a little longer allowing for more aggressive valve overlap etc. making it possible to change up and be more aggressive with your cam timing and profiles - many many different factors to think about. However that is some very fine tuning and normally only reserved for racing applications as well as older megaphone exhaust systems. ie. Norton Manx singles or Honda 5 cyl multies. The benefits of doing this on a modern bike are largely negated when you have cross over exhausts, 4 into 2 into 1, cats, and non-megaphone exhausts. Much why we see very short exhausts on modern bikes. The added control of the ECU and fuel injection, along with the sensor control make this kind of thing a non-issue on modern bikes - so it is my understanding that the exhaust pulse and management of that for tuning purposes in modern bikes is not an issue worth addressing as it really is insignificant due to the above.

If this was such a big issue the aftermarket exhaust industry and can industry would be non-existant. I know there is a lot of fashion and hype about that but in most cases a full exhaust will add hp without changing mixtures on a modern ECU bike. It of course changes the airflow and the tuning but the ECU accommodates for that appropriately in modern bikes. Maybe not bikes that are 15 or more years old but the R1200 for the most part (it is only my understanding) is not affected for mixture - It is affected and shows performance gains with better air flow (filters) =more oxygen and better exhaust flow = less back pressure more flow - easier to push that out the back end.

Like you said - none of us really know unless we get the data on the specific bike and do the tests right... so it is cautioned speculation I think based on our combined years of experience... wow kind of scary that actually. But in the long run I think we are all pretty safe with these things - maybe not perfect but I think... safe.
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Old 01-09-2013, 10:38 AM   #18
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If this was such a big issue the aftermarket exhaust industry and can industry would be non-existant. I know there is a lot of fashion and hype about that but in most cases a full exhaust will add hp without changing mixtures on a modern ECU bike. It of course changes the airflow and the tuning but the ECU accommodates for that appropriately in modern bikes. Maybe not bikes that are 15 or more years old but the R1200 for the most part (it is only my understanding) is not affected for mixture - It is affected and shows performance gains with better air flow (filters) =more oxygen and better exhaust flow = less back pressure more flow - easier to push that out the back end.
There must be some mid-range effects of intake and exhaust tuning on this bike. And it is certainly possible for tuning to effect the mid range (though admittedly I don't have any data on that effect on the R1150). I say that because the R1150RT and the R1150GS have much different intake tubes--for what reason other than tuning the intake?
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Old 01-09-2013, 11:00 AM   #19
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Talking 1200 GS mixture issure

RogerRT
Thanks for the post. My plugs are dual electrode which may be make a difference in read. That said, compared to your Autolite picture, my GS is showing lite grey even inside the plug, Based on the posts I have read here, I may be attempting to fix a normal burn as I have no spark knock or throttle issues with this machine; my old dirt bike days may be saying it is lean only in my mind. So, if it ain't broke don't fix it. The K&N may need another look though.

Thanks to all for responding to my question.

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Old 01-09-2013, 11:39 AM   #20
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If anyone is interested.

Exhaust pulses are used to keep the fresh intake charge in the cylinder during the valve overlap (both intake and exhaust valves open at the same time). The reflected wave acts as a damn at the exhaust port and would be tuned to arrive in the mid to low rev, dependent on what your looking for and there are equations to work it out. In brief its longer header for lower RPM, shorter for higher RPM. Higher RPM offers less time for it to happen so is simply of less use if any there. It occurs when there is a change in pipe diameter or a sharp turn. It will never enter the cylinder itself and stop fuel air getting in simply because the port reflects it back. How much use it is depends on many other aspects of the engine tune. Decat headers for example often show an increase in the low-mid range power because of the different and smaller Y joint so a stronger pulse is sent back up. It also obviously offers less restriction in flow with no cat in line so pumping losses are reduced at high RPM.
Intake length is partly about keeping the fuel in the inlet track. If you look at an engine with bellmouths (the intake pipes are simple bellmouths that exit in the airbox) on and look in while giving the throttle a good twist you will see a mist of fuel making its way out. Too short a track and the fuel can escape. As ever it isn't so simple though because there are pulsed involved here as well so a long intake track that will keep the fuel in at all times wont be the best for a high revving engine. Similar to the exhaust tuning longer is best for low-mid and short for high RPM.
Aftermarket exhaust manufacturers exist because they are in part free from what a mass production design has to cope with. They can play to a point with the tuned length and general packaging to suit what a purchaser wants I.E race bike or slow plodder. Whether its better or worse for a particular person is dependent on them. They also dont have so many regulations to cope with such as they can sell an exhaust without a CAT where the main manufacturer cant.
Both intake and exhaust tuning really do only offer small gains, even when tuned properly but they are noticeable to the butt dyno and a real dyno. As I said earlier though if not tuned properly they can make losses which is the opposite from what your actually trying to achieve. To get the best use from an exhaust and air filter change either a ECU fuel remap is required or something like a power commander fitted. There is a thread over on UKGsers with a company offering ECU remaps. There are dyno graphs posted that show even on a stock bike there are benefits to a remap showing useful gains never mind after component changes.
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Old 01-09-2013, 12:03 PM   #21
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I'm interested in your comments on exhaust and intake lengths, thank you. Makes sense, though it seems like the realm for an expert. The R1150RT has shorter larger diameter tubes compared to the R1150GS which has longer narrower intake tubes.

I saw the UKGSER stuff and there is a thread here too on someone who sent their ECU for remapping.

My opinion is that most who use a power commander and get improvement do so mainly because the vast majority of tunes add fuel. My Wideband O2 project showed that if you add 4-8% more fuel by changing the lambda set-point you get good torque gains throughout the RPM range but especially good between 2000-3000 RPM.
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Old 01-09-2013, 12:21 PM   #22
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Yes I agree it is mostly by adding fuel. The downside of the wide band route is that it doesn't really have much affect outside closed loop simply because the ecu doesn't look at them. Maybe not a problem for yourself and a lot of other riders especially on a big GS that isn't exactly a race bike. For some users though the retune is better if they are on the WOT a lot, generally driving hard. It's all preference and many will scoff saying it's not needed and a waste of time and money, others will see it as life saving and worth every penny/cent.
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Old 01-09-2013, 02:24 PM   #23
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Yes I agree it is mostly by adding fuel. The downside of the wide band route is that it doesn't really have much affect outside closed loop simply because the ecu doesn't look at them. Maybe not a problem for yourself and a lot of other riders especially on a big GS that isn't exactly a race bike. For some users though the retune is better if they are on the WOT a lot, generally driving hard. It's all preference and many will scoff saying it's not needed and a waste of time and money, others will see it as life saving and worth every penny/cent.
Actually when you richen the Closed Loop mixture with a wideband controller, it also adjusts the fuel in all Open Loop areas including WOT and Warm-Up through a process called adaptation. The 1150s and 1200s have that for sure and I suspect the 1100 does as well but haven't measured it yet. As an example if you set the wideband lambda to 0.94, WOT gets 6% richer and the warmup gets 6% richer after an adaptation period, I've measured the effect and presented recorded WOT and warmup AFR data.
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Old 01-09-2013, 02:45 PM   #24
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Originally Posted by carlesonra View Post
RogerRT
Thanks for the post. My plugs are dual electrode which may be make a difference in read. That said, compared to your Autolite picture, my GS is showing lite grey even inside the plug, Based on the posts I have read here, I may be attempting to fix a normal burn as I have no spark knock or throttle issues with this machine; my old dirt bike days may be saying it is lean only in my mind. So, if it ain't broke don't fix it. The K&N may need another look though.

Thanks to all for responding to my question.

Carlesonra
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Remember, reading plugs these days is different than from days of old when we had tetraethyl lead in our fuel. Also the old fuels were not blended with oxygenates. Also, many dirt bikes were 2 strokes...different animal altogether.

As for megaphones, (reverse cone megaphones actually), cam overlap and Manx engines on old Brit bikes, they were dealing with completely different flows and had no EPA to deal with. Also Hailwood, Agostini and the boys were often limited to engines half the size of the current boxer displacement.

Today, engines must comply. To do so, the state of tune is much milder, compression is lower, bore-stroke ratios are different, EGR is prevalent and we have engine fueling managed by computer, not the needle position, throttle valve cutaway and main jet size of the old Amal or Dellorto carburetors.

Those days are gone unless you tear off the EFI and install carburetors.

Aftermarket exhaust and fancy air filters do little more than lighten your wallet. If you want big performance, the boxer is not where it is at unless you're thinking turbo....

To extract meaningful additional power from a boxer, you'll need major engine work. To improve driveability and engine manners, follow roger04rt's suggestions. His work is backed up with charts, AFRs and other sophisticated measurements that are meaningful.

When you have spent north of $1000.00 on a fancy exhaust, your butt dyno is already biased towards at least 10 BHP gains before you even start the engine.

Installation of fancy air filters carry slightly less butt dyno increases.

Want a few free HP from your boxer? Change oil viscosity to 10w-30 or 5w-20. You gain several HP by reducing rheological losses.

def screwed with this post 01-09-2013 at 03:01 PM
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Old 01-09-2013, 02:50 PM   #25
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Aftermarket exhaust and fancy air filters do little more than lighten your wallet. If you want big performance, the boxer is not where it is at unless you're thinking turbo....
Mmm turbo : but no your right. If you want 180bhp go buy a K1600
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Old 01-09-2013, 02:54 PM   #26
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Yes I agree it is mostly by adding fuel. The downside of the wide band route is that it doesn't really have much affect outside closed loop simply because the ecu doesn't look at them. Maybe not a problem for yourself and a lot of other riders especially on a big GS that isn't exactly a race bike. For some users though the retune is better if they are on the WOT a lot, generally driving hard. It's all preference and many will scoff saying it's not needed and a waste of time and money, others will see it as life saving and worth every penny/cent.
I agree totally, this is really great to understand but it has all been gone over before in much more detail by much smarter blokes than me.

What I am saying I guess in a very verbose way is that the addition of an aftermarket air filter or pipe will retune a bike (for sure) but the bike ECU will retune it back and will change the mixture of the bike back to the prescribed parameters - as that is what the bike is constantly trying to do based on load, throttle, and sensors. Now if the bike is capable or not... I think so - some think not.

Everything that we have been talking about has been covered in minute detail here.

And if you are interested in the ECU reprogram (which will give you huge HP gains and other changes and combined with an exhaust and filter...) info can be found here.

One must either trick the bike or change the mapping. At least thats what I believe. And I am done here... no more room in my brain for anything but this.
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Old 01-09-2013, 03:08 PM   #27
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Originally Posted by Disco Dean View Post

...

What I am saying I guess in a very verbose way is that the addition of an aftermarket air filter or pipe will retune a bike (for sure) but the bike ECU will retune it back and will change the mixture of the bike back to the prescribed parameters - as that is what the bike is constantly trying to do based on load, throttle, and sensors. Now if the bike is capable or not... I think so - some think not.

...
On this point, you're right and I've measured it. In the R1150 and R1200 documentation, there is clearly description of the Adaptation Values that would allow the fueling to get back to the settings of the Lambda sensor after an Adaptation period.
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Old 01-09-2013, 03:28 PM   #28
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Originally Posted by Marki_GSA View Post
If anyone is interested.

Exhaust pulses are used to keep the fresh intake charge in the cylinder during the valve overlap (both intake and exhaust valves open at the same time). The reflected wave acts as a damn at the exhaust port and would be tuned to arrive in the mid to low rev, dependent on what your looking for and there are equations to work it out. In brief its longer header for lower RPM, shorter for higher RPM. Higher RPM offers less time for it to happen so is simply of less use if any there. It occurs when there is a change in pipe diameter or a sharp turn. It will never enter the cylinder itself and stop fuel air getting in simply because the port reflects it back. How much use it is depends on many other aspects of the engine tune. Decat headers for example often show an increase in the low-mid range power because of the different and smaller Y joint so a stronger pulse is sent back up. It also obviously offers less restriction in flow with no cat in line so pumping losses are reduced at high RPM.
Intake length is partly about keeping the fuel in the inlet track. If you look at an engine with bellmouths (the intake pipes are simple bellmouths that exit in the airbox) on and look in while giving the throttle a good twist you will see a mist of fuel making its way out. Too short a track and the fuel can escape. As ever it isn't so simple though because there are pulsed involved here as well so a long intake track that will keep the fuel in at all times wont be the best for a high revving engine. Similar to the exhaust tuning longer is best for low-mid and short for high RPM.
Aftermarket exhaust manufacturers exist because they are in part free from what a mass production design has to cope with. They can play to a point with the tuned length and general packaging to suit what a purchaser wants I.E race bike or slow plodder. Whether its better or worse for a particular person is dependent on them. They also dont have so many regulations to cope with such as they can sell an exhaust without a CAT where the main manufacturer cant.
Both intake and exhaust tuning really do only offer small gains, even when tuned properly but they are noticeable to the butt dyno and a real dyno. As I said earlier though if not tuned properly they can make losses which is the opposite from what your actually trying to achieve. To get the best use from an exhaust and air filter change either a ECU fuel remap is required or something like a power commander fitted. There is a thread over on UKGsers with a company offering ECU remaps. There are dyno graphs posted that show even on a stock bike there are benefits to a remap showing useful gains never mind after component changes.
Nothing sounds like a big Matchless, AJS or BSA single on the pipe. I get weak in the knees when I hear one (which these days is rare).

My Triumphs and BSAs used to spray fuel on my legs at idle from cam overlap but, my B'ville T120 would spin up to just short of 10,000RPM on pump fuel with a lightened rotating assembly, T&M 6 and 9 grind cams and aftermarket compound wound valve springs. Those were the days.
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Old 01-09-2013, 03:44 PM   #29
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Mmm turbo : but no your right. If you want 180bhp go buy a K1600
Now yer talkin'.

But, that is an ugly bike too however, the power is impressive.
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Old 01-10-2013, 07:44 AM   #30
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Nothing sounds like a big Matchless, AJS or BSA single on the pipe. I get weak in the knees when I hear one (which these days is rare).

My Triumphs and BSAs used to spray fuel on my legs at idle from cam overlap but, my B'ville T120 would spin up to just short of 10,000RPM on pump fuel with a lightened rotating assembly, T&M 6 and 9 grind cams and aftermarket compound wound valve springs. Those were the days.
Sigh... yes I know. Nothing quite like it. No amount of sound tuning by computer will ever get that wonderful sound of a big british single.... Goldstar, Manx.... Commando(twin)...or my nice little Ducati 250 with an open megaphone. Yummy to say the least if that is an appropriate word for it.

I was recently at the Vintage festival in Hockenhiem and they warmed up a Honda 6. I don't care what anyone says that is one of the magical wonders of the world - someone figured it out and someone made it happen. Magic.

Now if I can just read the fault code or write some new programming for my GS.... There is no virtual reality in a Honda 6.

Yes "Def" Those were the days.
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