Found a solution more or less accidently when I logged a ride. Helped fine with my XB12, but will not neccessarily work with every bike.
When the throttle is closed in overrun, fuel get's reduced according to the deceleration correction settings, by default 96%. (All images shown below are made with a much lower setting (40-60%), to get rid of excessive exhaust popping in overrun.)
When the throttle is opened again, there's a small lag until the deceleration condition ends and fuel will be delivered again. This is what makes riding at low speed quite irregular.
Image 1: logfile as logged when letting the bike run with a closed throttle.
http://ecmspy.com/download/gunter/images/decel_log1.jpg
Watch the pink line in the marked area, how it drops below the blue line (showing the fuel map's value). As soon as the idle region is reached (rpm < 1350, load < 20), fuel will be supplied again and the bike suddenly bounces forward. This also happens very similar if the throttle is opened, as seen in the event just left from the marked area.
Deceleration correction is defined by a value and by a region, where it is applied. Both engine speed and load must be below the line, defined by the four points of the deceleration correction region:
Standard setup of the deceleation region:
My attempt was to make it impossible to enter deceleration correction at low speed, by setting the load to 0 at an engine speed higher than will apply at the targeted speed:
When logging another ride with the deceleration region adjusted as above, riding was much smoother and throttle reaction more predictable as before. Especially slow turns will benefit from this refinement.
http://ecmspy.com/download/gunter/images/decel_log2.jpg
The marked spot shows where fuel kicks in again, as a much higher speed than before, where the change is much less noticeable.
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