Here's the story as quick as I can make it:
I live 35 miles from my garage space (my parents).
New battery (full overnight charge) and plugs installed a few days ago. Bike would idle fine, didn't take it out of the driveway. Didn't leave it on the tender while I was away. Today the tender said charging "less than 80%". Left it on for 30 minutes or so. I figured the new battery had to have a decent charge still so I fired up the bike to head to my apt.
16 miles of back roads and the exhaust note changed significantly at certain throttle positions. More pop pop poppy than the usual high pitched wine. Started sputtering at lights and wouldn't idle without the choke. If I kept the RPMs up, it seemed happier than when I was under 4000rpm.
Finally it stopped running near a gas station/car mechanic. Plenty of fuel. Plugs looked smokey grey when I pulled them. Put my battery on the charger (again reading less than 80%). Let the battery charge for 30 minutes or so. Kicked it back over and it idled again.
Rode 10 more miles (8 miles on the highway at 60mph) and the same exhaust note change happened again. Pulled off the next off-ramp moments before it sputtered out again. This time I would get intermittent bursts of acceleration depending on throttle position. But in the end it stopped running 1/4 mile off the highway. No head/tail lights, no indicator lights.
I'm charging the battery again overnight to hopefully get the bike to my apt. Any suggestions?