But aren't the adjustments by the O2 sensors made by the ECU, not the O2 sensors themselves?
Yes the ecu just deals with the data from the sensors. As far as I know (and I clearly do not know everything) the O2 sensors on the bike work essentially as a on off switch. The sensor reads and sends a voltage that the ecu interprets as a CO value, then the ECU takes that value and looks up what the program wants the value to be. If it is out of the range desired by the programmer it adds or removes fuel until it see's the value. This is how the aftermarket O2 sensors work IIRC they take the sensors value output and lie to the ECU so it thinks the bike is leaner than it is. The narrow range may be by design because too rich might (no idea) damage an existing catalytic converter where a de-cated bike should not be harmed.
couldn't the ECU just be reprogramed to adjust the CO to higher levels like you say by a tuner that flashes the ECU?
I am not a programmer so I can not tell you why not but I would think that would be the best scenario. Rapidbike accesses and probably tricks the O2 sensors giving you control through a steal the information and lie to the ecu plan but gives more flexibility as well as keeping the O2 sensors helps the bike maintain a good air fuel ratio. In theory.. sorry my inner skeptic waiting for more long term results. I like proof more than testimonials.
A narrow band sensor is what you have on the bike and it works more like the on/off switch. A wide band will read much more accurately and faster so you get better results. This is what a dyno uses. I am not sure if it is cost reasons we do not get wide band sensors on the bikes or durability. My dyno goes through 1-2 sensors a year and if I run race gas/aviation fuel that drops to a couple hundred runs. If that were a street bike you would NOT like the added costs.
In a perfect world the O2 sensors would be running (wide band probably) and the ecu would be able to be set for what ever CO values you want. The ecu could then self map and you truly could auto map for what ever you want.
lean for mileage or to be kind to mother Gaia.
Rich for power and a smooth running bike
In between for the person who wants it all but cannot decide between morality and selfish pleasures.
I am not sure why this is not available (still not a programmer) but there are probably many reasons, the largest one being Governments do not care if your bike runs good only that the loudest voices make sure it does not pollute. What you get from the factories (all of them) will never be the best they can build it is more the best compromise they can build. Some times they get it right and others they focus too much on areas that they think you care more about.