So it should be activated so it remembers the level then when it's placed on the sidestand? I remember the good old days of a reserve tap and 20 miles to find fuel!!
no its just ALWAYS going to be be incorrect with tank the shape it is, and or exacerbated with the incorrect float position on small tank bikes...
the float can ONLY send linear drop info (whereas the strip bend via its S curve and software does something a bit different), so, small tank bikes that don't have the twin socket ZFE alternate inputs and logic, there is no other linear signal to non linear tank level conversion happening to suit the float's belief of what isn't really isn't going on
Don't forget the bike through use gets to understand what Full and Empty is over time and constantly fights itself to hone the perfect Range from Full to Empty ... ( I guess that's why they used a Strip its much easier to get it stable regardless - and when you get your head around the bits coming up, why the strip is an S shape from the filler neck)
When converting it to a Float sensor with the bike empty, the Float should be at the bottom - At start up inside the ZFE this creates the New Empty signal for the bike to remember forever (in a normal world), but don't forget this is BMW hardware and software and they never knew what they were doing to start with - in reality the Float might really be just hanging on the breather pipe. But its still an Empty signal today as far as the ZFE knows.
Then I go and fill the bike half full. Now with the bike running and level, this top up becomes the highest reading the bike has ever seen (via this Float) so it now reads Full Up. I ride off and do 50 miles using a bit, then I decide I have a longer trip, so stop and fill to 3/4 full and this is now magically the New Full. My Range is wondering how life works....
But Empty is still going to be Empty so its not really going to let you down... but you won't believe that as its readings have been rather odd up to now. And the Range is currently somewhat all over the place
Now the fun, except Empty may not be really have been Empty. If when it was fitted you got this slight hang on the breather hose (that are so stupidly fitted in the tank), the bike may have believed that was the lowest it could ever have. But as I run towards Empty and the gauge starts heading for Empty, with the fuel sloshing about (proving a lubricant) and with the socking roads (jarring everything) the float slips past the breather hose and creates a new Empty reading in the ZFE. So my range can leap a up a bit as the bike suddenly gauges there's more in there than it had previous believed.
And as far as you dare go each trip, the braver you go becomes the new Empty each time.... Unless it really had a real Empty signal stored when you fitted things correctly. e.g. to a tank with a smidge of fuel to get a valid Empty value where the tank pump pick up was still drawing something when the bike was upright - and it didn't hang on the breather hose that first time !!!
All this silliness goes on and on, then one day you absolutely brim it on the centre stand (fighting the pump nozzle and 3 minutes of topping up through the bubbles long after the 5 normal pump clicks you usually stop at have past) and ride one mile home. That just became the new Full all over again. Except its not - as when you idled on the side stand unlocking the garage to park up, the float gets rammed in the corner of the tank higher than ever before and another New Full signal is set up....