How about spark plugs. How old are yours?
Albuquerque, NM
They are also due, but I don't think they were when I saw the drop. I saw an appreciable drop in San Diego, but I was riding hills as opposed to here on the Gulf Coast. As for crossing the magic RPM-ness, (>~72mph), un, that would be speeding. I would NEVER do that!!
[SIGPIC][/SIGPIC]
Honda 2007 Shadow
Honda 2006 VTX
Honda 2013 F6B
The battery is still in the circuit but it's base voltage and no longer has input once the potential of the alternator is online. So it is " out of the loop".
Might be worth trying a new O2 sensor. I don't see that Honda monitors for slow O2 response.