View Single Post
Old 01-08-2013, 08:17 PM   #14
roger 04 rt
Beastly Adventurer
roger 04 rt's Avatar
Joined: Nov 2011
Location: Massachusetts
Oddometer: 2,371
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
roger 04 rt is offline   Reply With Quote