FWIW, here's what the wideband A/F numbers show on my engine....
Upon cold start the numbers start in the low 13s with the choke fully engaged. As the engine warms, and the choke opens, the numbers slowly climb to around 15. When I kick it down to normal idle the numbers drop to around 14.3. That seems to be where it idles the best.
At partial throttle cruise, the numbers stay in the 14.3-14.8 range. If I mash the skinny pedal, it drops to around 13, then recovers to the mid-14s in just a few seconds. Coasting down a hill will produce numbers as high as 15.5-16.
I have no idea how those numbers compare to narrow band numbers, but I bet 86 could tell us.