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Old 01-07-2013, 09:13 AM   #1
carlesonra OP
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Question 2009 GS lean mixture, harmful???

While checking valves on my 2009 1200GS at 40,000 miles, I noticed spark plugs showing a lean mixture. I have a K&N installed but no other change and realize manufacturers have clean running as a priority. Question is: are other riders showing light spark plug coloring which is kinda normal or Is this something that needs attention and if so what? I have not noticed any spark knock when pulling at lower rpm.
Thanks for your time in responding.
Bob Carleson
Arroyo Grande, CA
R1200GS, R80RT, DR650
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Old 01-07-2013, 09:34 AM   #2
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It is generally understood that current piston engines are fueled lean to meet emission requirements. In the boxer engine, this can be troublesome causing detonation, higher combustion chamber temperatures, driveability issues and reduced engine output. Later boxers employ knock sensors to detect and offset the issue of detonation.

In our attempts to improve performance, many boxer owners install free flowing exhaust systems, high flow air filters and other gadgets in an attempt to make more noise and more power.

Upon doing so, we see questions and comments such as yours regarding the appearance of lean fueling conditions. And while few boxer owners report engine damage, there seems to be an increase of the installation of aftermarket pipes and air cleaners. These pipes and air cleaners promote more engine air flow but do nothing to increase fuel flow. If you insist on aftermarket pipes and air cleaners, be prepared to spend more on electronics to increase fuel delivery along with the increased air entering your engine.

Over Christmas, my son trailered his Honda V-twin here to Alabama. One morning it would not cold start. Removal of the air cleaner showed why. The oil from the K&N had settled in the carburetor and choked off the pilot jet as well as left deposits on the carburetor slide. A spray with carb cleaner got things running again. But, it was evident from a plug check that the A/F mixture was way off.

If you insist on aftermarket air cleaners, be sure they provide effective cleaning of the air entering the engine. Some studies show these aftermarket air filters pass considerable dirt compared to the OE paper air filter. You have been warned.
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Old 01-07-2013, 09:37 AM   #3
Disco Dean
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This is normal.

Your bike will compensate for any modifications you do to the bike ie. exhaust or filter will not change the mixture.

As noted here in a number of posts - BMW and other manufacturers run their bikes quite lean - in my experience BMW has always done this. Mainly for emissions regulations and pollution control.

One of the reasons some use "booster" plugs and such to trick the bike into running a bit richer. Again posted on here quite a bit.

Do not worry - and if you are really concerned take it in for diagnositics and they will be able to tell if all is well pretty quickly.

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Old 01-07-2013, 09:38 AM   #4
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Originally Posted by def View Post
It is generally understood that current piston engines are fueled lean to meet emission requirements. In the boxer engine, this can be troublesome causing detonation, higher combustion chamber temperatures, driveability issues and reduced engine output. Later boxers employ knock sensors to detect and offset the issue of detonation.

In our attempts to improve performance, many boxer owners install free flowing exhaust systems, high flow air filters and other gadgets in an attempt to make more noise and more power.

Upon doing so, we see questions and comments such as yours regarding the appearance of lean fueling conditions. And while few boxer owners report engine damage, there seems to be an increase of the installation of aftermarket pipes and air cleaners. These pipes and air cleaners promote more engine air flow but do nothing to increase fuel flow. If you insist on aftermarket pipes and air cleaners, be prepared to spend more on electronics to increase fuel delivery along with the increased air entering your engine.

Over Christmas, my son trailered his Honda V-twin here to Alabama. One morning it would not cold start. Removal of the air cleaner showed why. The oil from the K&N had settled in the carburetor and choked off the pilot jet as well as left deposits on the carburetor slide. A spray with carb cleaner got things running again. But, it was evident from a plug check that the A/F mixture was way off.

If you insist on aftermarket air cleaners, be sure they provide effective cleaning of the air entering the engine. Some studies show these aftermarket air filters pass considerable dirt compared to the OE paper air filter. You have been warned.
plus one on that
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Old 01-07-2013, 10:05 AM   #5
Disco Dean
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Originally Posted by def View Post
Upon doing so, we see questions and comments such as yours regarding the appearance of lean fueling conditions. And while few boxer owners report engine damage, there seems to be an increase of the installation of aftermarket pipes and air cleaners. These pipes and air cleaners promote more engine air flow but do nothing to increase fuel flow. If you insist on aftermarket pipes and air cleaners, be prepared to spend more on electronics to increase fuel delivery along with the increased air entering your engine.
Def,

The fuel and mixture monitoring sensors on the bike - of which there are a few - are all situated after the air filter and before the exhaust - cat and free flowing aftermarket cans.

The computer in the bike continually monitors the system and adjusts the fuel mixture to suit - no change in air filter or exhaust will change the fuel mixture at the engine. The bike is continually compensating for this.

That is why these bikes continue to be perfectly tuned when starting cold, or in colder or warmer ambient temps (barometric pressure) as well as not being affected by altitude - the wonders of electronic fuel injection.

The BMW and other bikes even have a delay in this change depending on other factors like time you have run the bike while riding and consistency of your riding - ie. if you have done long hauls of highway riding the bike will delay the change in fuel/ignition due to riding style. That is why when you sometimes leave the highway and go through a few stops the bikes seems to be running extra lean or doesn't run right - until the computer figures out you are not on the highway again and changes - Harleys are notorious for taking a long time - all pre-programmed into the bikes.

As I noted many posts ago - when we attempted to change to fuel mixture characteristics of our BMW R - race bike by modifying both the exhaust and air chamber/filter we could not do this no matter how aggressive we were - the bike adjusted for it in all respects. The only way to do this is by either tricking the sensors - or by reprogramming the computer.

So aftermarket filters and exhausts (provided they have O2 sensors) and the filters actually filter the air - are completely safe and will not change the "leaness" mixture in the combustion chamber at all.

The bikes are too smart.

Now oil in the filter bunging up a carb is another issue and I do not use K&N because of those exact issues before and numerous testing that suggests either foam or standard oem paper is better but this isn't an air filter thread is it...
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Old 01-07-2013, 11:11 AM   #6
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Originally Posted by Disco Dean View Post
Def,

The fuel and mixture monitoring sensors on the bike - of which there are a few - are all situated after the air filter and before the exhaust - cat and free flowing aftermarket cans.

The computer in the bike continually monitors the system and adjusts the fuel mixture to suit - no change in air filter or exhaust will change the fuel mixture at the engine. The bike is continually compensating for this.

That is why these bikes continue to be perfectly tuned when starting cold, or in colder or warmer ambient temps (barometric pressure) as well as not being affected by altitude - the wonders of electronic fuel injection.

The BMW and other bikes even have a delay in this change depending on other factors like time you have run the bike while riding and consistency of your riding - ie. if you have done long hauls of highway riding the bike will delay the change in fuel/ignition due to riding style. That is why when you sometimes leave the highway and go through a few stops the bikes seems to be running extra lean or doesn't run right - until the computer figures out you are not on the highway again and changes - Harleys are notorious for taking a long time - all pre-programmed into the bikes.

As I noted many posts ago - when we attempted to change to fuel mixture characteristics of our BMW R - race bike by modifying both the exhaust and air chamber/filter we could not do this no matter how aggressive we were - the bike adjusted for it in all respects. The only way to do this is by either tricking the sensors - or by reprogramming the computer.

So aftermarket filters and exhausts (provided they have O2 sensors) and the filters actually filter the air - are completely safe and will not change the "leaness" mixture in the combustion chamber at all.

The bikes are too smart.

Now oil in the filter bunging up a carb is another issue and I do not use K&N because of those exact issues before and numerous testing that suggests either foam or standard oem paper is better but this isn't an air filter thread is it...
Sorry but your statements are completely at odds with my own and many others experience as far as the 1200 GS is concerned. Yes they can compensate but not indefinitely and a free flowing air filter at sea level will definitely take it out of bounds. There is only so much extra fuel in the map bins and once your outside the boundary your into mixture problems. O2 sensors by the way only trim mixtures in a closed loop situation I.E cruising. Outside this area they have no affect at all as they are only lambda sensors and not wide band sensors.
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Old 01-07-2013, 12:00 PM   #7
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Originally Posted by Marki_GSA View Post
Sorry but your statements are completely at odds with my own and many others experience as far as the 1200 GS is concerned. Yes they can compensate but not indefinitely and a free flowing air filter at sea level will definitely take it out of bounds. There is only so much extra fuel in the map bins and once your outside the boundary your into mixture problems. O2 sensors by the way only trim mixtures in a closed loop situation I.E cruising. Outside this area they have no affect at all as they are only lambda sensors and not wide band sensors.
As far as I know the BMW has a barometric pressure sensor (altitude) in the main comp unit, the O2 sensors, intake temp and pressure sensors as well as the knock suppression sensors and engine temp sensors to balance and accommodate the variables of operation. (As far as I know) Just my experience of course and I am not a BMW engineer or tech so do not have access to the actual figures and mapping comparisons - however my own experience on the track and the dyno with the BMW Cup bikes saw no change in the mixtures with various number of exhausts, cut and reformed air-boxes, and more than a few air filters including no filter at all. This was a few years ago. This involved many long hard hours in the shop and the only solution was getting access and clearance from BMW to use the BMW computer program to modify the mapping - they didn't want to do that of course.

My comments also come directly from a very good friend and racing buddy of mine who is the owner of a multi brand BMW dealership and his main BMW tech. As I posed the same questions in response to our experience with the 1200 on the track to them and my sometimes rough running bike after long hauls.

Maybe we didn't get outside of the parameters you talk about - perhaps - but with my own R1200GS "2006" I also saw no visible signs or change in spark plug colour with the addition of a K&N, OEM paper and now my oiled foam air filter - or my full cat-free Laser exhaust and headers. And that accounts for over 100k of mileage and many different filters and two exhausts - and approx 7 sets of plugs as I change them every year.

As the BMW paper air filter as tested and commented on this forum flows more air than an oiled K&N or even my oiled foam filter - I would think that would richen the bike and not lean it out - but again no change.

After all is said and done - I don't have specific data that I can show you to back any of my comments so they are just that. And, you know we could have screwed it all up too... you never know.

Take it for what you will.
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Old 01-07-2013, 12:56 PM   #8
Marki_GSA
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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.
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Old 01-07-2013, 01:09 PM   #9
MotorradMike
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The OP has an '09 bike.

Some of the responses in this thread are about older bikes, including one with a friggin' carburetor.
Best leave the older BMW boxers out of it as they assume air mass by measuring throttle plate angle.
Apparently, that has been improved upon.
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Old 01-07-2013, 01:16 PM   #10
Marki_GSA
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Mine is an 09 and that's what I am referring to. The 2008-2009 bikes were the worst for running lean out of all of them. The cam head improved a bit over them
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Old 01-07-2013, 02:33 PM   #11
Chip Stevens
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Spark plug color is not the best way to determine fuel air ratios. In aviation we determine rich or lean off cylinder head tempature peak. If you google Gami Injectors and spend some time researching you will see that many turbocherged aircraft are running 50 degrees lean of peak where the tempatures are cooler then at peak. All this is irrelevant if you are running less then 75% power. Power is determined by RPM and manifold pressure. Much above 5000 ft a naturally aspirated engine can't get more then about 75%. In other words if you are below 5000ft running full RPM and full throtle for more then two minutes you aren't likely to do any damage rich or lean. chip
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Old 01-07-2013, 05:41 PM   #12
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I have an 09 GSA. OEM filter and stock exhaust. The plugs are light colored. It also pings at low rpm and high temperatures.
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Old 01-08-2013, 10:52 AM   #13
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Originally Posted by MotorradMike View Post
The OP has an '09 bike.

Some of the responses in this thread are about older bikes, including one with a friggin' carburetor.
Best leave the older BMW boxers out of it as they assume air mass by measuring throttle plate angle.
Apparently, that has been improved upon.
Mike, While my comments included an engine with a carburetor, the example was intended to show that oiled air filters can cause problems and pass more dirt than the OE filter. As for the newer BMW boxer engine management, they still run lean to please the EPA.
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Old 01-08-2013, 08:17 PM   #14
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Most of Disco Dean's comments are correct.

There is some good information in this thread and some wrong information. I've ridden around most of the last year with a GS-911 and Innovate Motorsport LC-1 Wideband O2 sensor logging AFRs continuously. My motorcycle is an R1150 but it would be hard to believe that the newer machines don't have all of the EFI features of the R1150. I've seen R1200 GS-911 data and there are more features reported.

Here are some important things to know:

1) there is not an intake manifold MAP (manifold absolute pressure) sensor. The Motronic's use the TPS and RPM to do the basic fueling.

2) there is a barometric pressure sensor on the ECU and it does adjust for altitude.

3) on a typical ride the motorcycle is closed loop 40-50% of the time. When closed loop the mixture is always a few points from lambda=1 which is 14.7:1 for pure gas and 14.1:1 for E10. This is true even if you add intakes and exhausts. My data says that closed loop has roughly a +-20% range. Very large.

4) when closed loop, the Motronic learns how far off your particular engine is from standard: battery, fuel pressure, fuel type, airflow, sensor errors, etc. What it learns in closed loop it applies broadly to all Open Loop fueling—including WOT and warmup. The correction factors are called Adaptation Values and are referred to in the 1150 manual and for the 1200 I've seen them in the GS-911 documentation.

5) closed loop adjusts very quickly, less than a few seconds in all cases. Long Term adaptation values take longer depending on how you ride. Steady driving at various speeds, RPMs and load helps it learn faster.

6) All these bikes run equally lean from R1100 to R1200 but some run better on the lean mixture than others. For example the 1150s and 1200s from '04 on have two plugs per cylinder which help it burn the lean mixture. 1200s on have two O2 sensors. Closed loop AFR and adaptation get calculated per cylinder. This way you don't have one cylinder leaner than standard and one richer than standard.

To remedy the lean running the simplest thing to do is to replace the stock lambda=1 sensor with a Wideband sensor that allows you to program lambda 4-6% more fuel works wonders. The cost is about $160 per O2 sensor. I've got all th info published in two Wideband threads here. So a mixture between 13.8 and 14.1 (for gasoline) leads to a great running bike--no pipes, no filters, no dyno tuning needed.

If you want my opinion on why intake filters and exhausts affect running ... And since I haven't seen anyone log data on this ... I would guess that since the intake and exhaust systems are tuned, putting aftermarket parts on leads to LESS air in the cylinder in the mid range. Less air means less power. Until someone logs the AFR at various RPMs and loads, all we'll have are opinions.

Regarding the aviation comment, its at about 7500 feet where naturally aspirated engines hit 75% power, however the guest of that comment is correct.

roger 04 rt screwed with this post 01-08-2013 at 08:23 PM
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Old 01-09-2013, 04:24 AM   #15
roger 04 rt
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Quote:
Originally Posted by carlesonra View Post
While checking valves on my 2009 1200GS at 40,000 miles, I noticed spark plugs showing a lean mixture. I have a K&N installed but no other change and realize manufacturers have clean running as a priority. Question is: are other riders showing light spark plug coloring which is kinda normal or Is this something that needs attention and if so what? I have not noticed any spark knock when pulling at lower rpm.
Thanks for your time in responding.
Bob Carleson
Arroyo Grande, CA
R1200GS, R80RT, DR650
Light spark coloring is normal in engines with O2 sensors. As has been said many times. Through this thread.

Interestingly, I have used a Wideband O2 sensor to add 6-8% to my fueling and the plugs still are light. (Below) how do your plugs compare to mine?

The mixture set by the narrowband O2 produces the highest exhaust gas temperature. Go richer and the EGT drops and surprisingly to some (but not pilots of piston engines) the EGT gets cooler as you go leaner.

Here is an Autolite Plug with 2,000 miles of mostly local driving at 13.8 which means 6% richer.
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