BMW R1100S STAINTUNE, INDUCT ( UPDATED )

My bike also has been fitted with a large inlet duct made by Boxer Performance known as the INDUCT. This really lets the bike breath at the top end. The performance difference was very obvious during the remapping. As we got closer to the required fuel map, I was closing the throttle increasing earlier before corners. The sort of mod for people who use their R11S hard. The duct is shown below.

This duct has a far greater cross sectional area at the bend around the battery, where the std duct gets so small you’d wonder how the bike makes any power at all, let alone 90 rear wheel. The dyno graph below will look like a backward step to many, which is why I didn’t post it originally. Red is INDUCT, STAINTUNE and FIM eprom. Blue is STAINTUNE and FIM eprom. Green is STD.

This is due I believe to the effect of reduced airbox pressure ( at the dyno, compared to the on road reality ) and overly rich fuel mixture ( due to the air pressure sensor location, see below ), both of which kill power on the dyno. I can assure you that it certainly goes harder than before. Does much better wheelies too.

You might think it strange that the bike would come from the factory with such a restricting feature. The reason, though, is most likely to do with the location of the ambient air pressure sensor. On BMW’s equipped with motronic 2.4, the air pressure sensor is mounted inside the ECU itself. Therefore, it has absolutely no idea what is going on inside the airbox. The BMW engineers found no doubt that a large and free air inlet made the bike run rich at high throttle/low road speed and lean at high throttle/high road speed. The variation would probably have been far too large for them to consider as a viable production option. So instead of changing the fuel injection hardware slightly to allow recognition of inlet conditions, they chose to restrict the engine. No doubt an accounting decision.

The duct retails for $645. An eprom to suit is available from FIM for $240. To order an eprom, you need to supply the 7-digit number from the ECU cover. This is due to the fact that the eproms used in the Bosch ECUs were changed in mid 2000. Check the R1100S ULTIMAP BY FIM page for more eprom details.

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