Probably running rich, would be worthwhile giving it a tune up.There is an easy way to know whether you have the mixture right. With the bike idling at 1000 rpm press the green start button, if the mixture is right the revs will remain the same or rise slightly. If the revs rise a lot or drop the mixture is out.This is a feature that BMW built into the bike and as long as it is idling at 1000rpm or above the starter will not engage. Dirty air cleaner can also cause rich running.
Regards Martin.
