I was unfortunately in need of a tow home today from work on my VN750. I have about a 30 mile ride into work and noticed in the last half mile some "funniness" like I had hit reserve, but I had a full tank and was already in the reserve position. I chalked it up to erratic wind, however when I got nearly to my parking space it felt like a cylinder cut out for an instant and recovered. At lunch I went out to see what was up with it and found that starting it was not going to happen, the battery was drained pretty well. The battery is a Sears die-hard from last year.
In any case, I went in and grabbed a little lead acid battery from work (not a automotive one), let it sit a minute charging myself and I was up and running. I set the choke pretty high to keep a nice high RPM and started heading home thinking the battery was bad. I made it about 2 miles and it died in an intersection, in the end I ended up on a flatbed being towed home.
Upon getting home, the battery was 11.x volts, so too low. I pulled it and threw it on a charger, it was taking a charge very well. I stuck in a 12V (nominal 16v) supercapacitor bank I'd made (long story, I ran the bike off it for years for starting) and although I would start in the 14+ volt range, I could watch the voltage drop until it stalled. No charging.
I've been going through the forums and youtube videos about Stator failures and I was in the .6ohm range between any of the yellow wires, HOWEVER, my voltmeter indicates around 13.85 Mega Ohms between any phase and ground, which supposedly means a bad Stator. When I run the bike though, with the stator wire harness disconnected, I get good voltage out of it and it goes up proportionally with RPM. I read somewhere else about using a 12v test light to see if there was voltage flow, and ran this in line with the milli-ampre range on the voltmeter. No voltage was passing between any phase and ground.
I don't understand the 13.85 Mega Ohm resistance between ground and any of the phases.
In any case, The wire harness looked pretty nasty with corrosion, so I was down there cleaning the connections with Hoppe's No9 (had it handy), pipe cleaners, and a bronze brush.
Upon hooking it back up, it started AND I get charging. What's normal? I was 14.x volts @2000 RPM, but low 13.xV at perhaps 1100 RPM ( idle). The bike was running a bit slow for a bit and I noticed that when it would drop below about 1000RPM the voltage was insufficient to really charge it, meaning the low end of 12.x volt range.
I don't really trust the bike now for going to work (main use), and I'm not sure what to check next. I have a feeling that the ignition switch might have some issues, as I've had a few cases where I hit the starter and "nothing" happens until I take the key out, fiddle with it, put it back in and then can start.