Battery/charging

so i picked up a 82 550ltd-c back in June that had been setting a few years. I replaced the battery , a leaking petcock, cleaned and adjusted carbs. The bike has ran like a top for the past few month but the past few days id have to boost the battery off to get her running. The bike never sat more than 4 or 5 days without being started. Mostly short trips around town 10-20 minute trips. Once the bike is running it runs fine. Checked the voltage of the battery after a short ride it was setting just over 14v. Granted I didn't let the battery rest after the ride. I'll re-check in a hour or so. When I load tested by trying to start the bike the voltage dropped from the 14v to 9v. The engine turns over but very slow then stops. I just have a hard time thinking its the battery. It's been in the bike a little less than 3 months and havnt had an issue until a few days ago.

So update after recheck voltage. Still setting at 14v. Took the hot lead off the battery and checked if there was anything pulling power and according to the multimeter somethins os pulling .5 so o guess ill have to hunt that down

So I found some hot spots just gotta run them down. Anybody have any ideas these were hot with the key on. And when the key is off they pull about 13v

So i downloaded the wiring diagram. The best i can tell this looks like the wire going from the battery to the ignition switch. I guess the next step is to ask a dumb question lol. Can you bebuild or re wire the ignition switch. And is there any way to confirm this is the problem before buying new parts

My first suspicion would be the battery itself going bad. Since you have 14v to it while riding, the first-glance at the charging system would indicate that it is ok.

Yes, you can take apart an ignition switch if you are very patient and don't need it to look perfect. I'm not very patient so when I do it, it works, but looks buggered up.

However, if you end up having low voltage to the battery, it won't be the ignition switch causing it. Voltage drops at the ignition switch would cause the charging at the battery to be too high.

One failure mode of the now nearly 40 year old reg/rec is that it can initially show 14v at the battery, but during a long ride the output to the battery slowly drops down to nothing. I've seen at least two fail this way on Kz550's. The way to tell is to somehow mount a voltmeter on the tank and connect it to the battery. Initially you will get 14v and as you ride it will slowly drop to 12v.

If that's what you have, then you can get a Ninja 250 or 500 reg/rec from the early 2000's for like $10. They work well but will require splicing wires since the connector is different.

The fact that the battery drops to 9v under load suggests that it needs to be replaced.
There may also be other gremlins adding to the problem.

A failing battery was my first thought also but its less than 3 months old, so I started looking elsewhere. I did find that the wires in the attached pictures would get hot to the point of melting with the key on. ( battery to ignition switch)I really don't think its the charging system unless it just took a dump over night. Has done fine for months butlike you said it almost 40 years old. After i figur why the ignition wires are heating up. Grounded switch maybe?? Ill try the multimeter on a ride to see if the volts drop thanks for the reply and info

Never feed or get gremlins wet lol and I got this one wet yesterday.

What method did you use to boost the bike's battery?

Have the battery tested. Ed

Boosted from my puck up it wasn't running. I don't have a booster pack or a charger . That was my only option to get it going at that moment. I know its hard on the battery doing that.

on my next rotation off work I'm going to have it tested. The thing that really concerns me is the wires heating up. I had the key on for about a minute the bike wasn't running and the wires were hot enough to feel through the plastic fuse holder. In the top pic you can see where it got hot enough to melt the plastic.