Just found this interesting detailed info on how the MIU G3 in a Moto Guzzi V750 works. Assume the same in a Vespa HPE

https://manuals.wotmeworry.org.uk/useful%20info/magneti_marelli_miu_g3_information_14854.pdf



Also on guzziforum.de found this quote (translated by google) from the guy reverse engineering the MIU G3 of a Guzzi (V7 III?)
Quote:
At air temperatures <= 18°C ​​and outside the range 1200 <curr_rpm> 5500 no closed loop adaptation is made.
which I gather means lambda o2 sensor is not used above 5500rpm on the Guzzi. I had seen people mention iirc 6000rpm for a GTS on this forum so is nice to see what has been found inside the ecu itself.