BMW R 1200 GS LC (Liquid Cooled) Tuning

In 2004 BMW released the R 1200 GS, after having had great success in the world market with its predecessor, the R 1150 GS.  Sales of BMW's dual sport range accelerated after Ewen McGregor and Charley Boorman  did “The Long Way Around” traveling across the US and Russia. They later followed this up with "The Long Way Down", where they traveled through Africa.

In 2013 BMW introduced the R 1200 GS LC, their first liquid cooled version of this odd motor configuration since its initial introduction in 1923.

In this article we will cover the fuel tuning of the R 1200 GS LC (Liquid Cooled). 

After tuning many of the previous models, I was quite keen to see what BMW had done in terms of Air Fuel Ratios (AFRs) as the predecessors were pretty lean throughout the rev range up to eighty percent throttle opening. My first impression of the LC was that it was a lot smoother, and that it had a lot more horsepower and torque. As you can see in the graph below, it also gained an extra 500 RPM.

Graph showing the older, air/oil cooled motor in Blue, and the newer liquid cooled motor in Red

I must mention that this LC is a huge improvement on the older bike. The new bike is equipped with ride by wire throttle which also enables different riding modes. In addition, the LC has a quick shifter which in my opinion is really not necessary on a bike like this, a quick shifter lends itself more to sporty machines which this bike is not. However the bike does make quite a nice, self satisfying burble while using the shifter.

After doing the first pull on the dyno, I was quite surprised to see that the AFRs were almost identical to the older models. I was expecting to see a richer mixture in the high load areas. Due to strict emissions regulations, manufacturers have to comply with the usual, agreed “stoichiometric” air fuel ratios (14.7) in all currently manufactured vehicles. Being water cooled, I was surprised to see this AFR carried into the high load areas.

We then fitted a Dynojet Power Commander V (PCV) in order to take control of the fuel injectors' duty cycles, and to correct the factory Air Fuel Ratios. I must add that although this bike is simple in design, it does make a Power Commander installation somewhat challenging if it is neatness you are looking for. All the injector and throttle position plugs are exposed, it could look unsightly if the installation is not done correctly and with neatness in mind.

Once the PCV was installed, we could now start mapping the bike. Because it is a Boxer motor, we always choose to map the cylinders individually. With fitting a Power Commander, the oxygen sensors are eliminated and this allows me access into the exhaust via the standard lambda fittings. This is important as it enables me to get an accurate AFR footprint straight from the bike.

We started mapping Cylinder 1 which is on the left, and targeted an AFR of 13.5 in the low load area, and enriched up to 13.1 - 13.0 AFR in the high load area.

BMW seem to carry a 14.7 AFR all the way up to 80% throttle position (TP). Even with the ECU now being in 'open loop' (oxygen sensors disconnected), the factory map was still lean. The richest I saw from the stock map was a 13.6 AFR.

You will notice from the above map (Cyl 1) 2% to 15% TP and up to 5250 RPM (Low load) requires less fuel, and from 20% to 80% TP up to the rev limiter (High load) requires a substantially larger amount of fuel to be added. Only at 100% TP will you notice that I was required to remove some fuel in order to get to the desired AFR.

On Cylinder 2 the story is somewhat different. At 0% TP I had to remove a considerable amount of fuel to correct the AFR at idle. On this cylinder, the entire fuel map was richer than the left. This can be seen by the negative values in the (Low load) as well as smaller corrections in the (High load).

As the AFR was being corrected, you could literally feel the bike getting smoother and smoother, and another thing I noted was that the water temperature dropped by +/- 5 degrees. 

The graphs below are before and after the mapping session, Blue = Before and Red = After. Unfortunately I have not attached every throttle position for the sake of time.

The first graph is a stepped run in increments of 250 RPM at 5% TP and to make things a bit clearer, following the graph is the raw data.

Graph at 5% throttle position, Blue being before, Red being after.

Raw date at TP of 5%

At the above TP we are targeting 13.5 AFR up to 5500 RPM.

The graph below is at 40% TP and unlike the run at 5% TP it is not a step test but rather a loaded roll on with 10% load and here we are targeting a 13.0 AFR.

Graph at 40% throttle position, Blue being before, Red being after.

Raw data at TP 40%

Finally the graph at 100% TP showing peak gains, Blue being before, and Red being after. 

In my opinion, every motorcycle engine that has to comply with emissions legislation needs some sort of fuel tuning module like a Power Commander (my choice), and this is particularly true for BMW's Boxer engines.

Thanks for reading,
Julian

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