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Hey everyone! I'm pretty new to the forum. Just bought a 1980 cx500 a few months back. For the most part, it runs like a dream. Just a few minor kinks here and there.

Speaking of... My bike is a little funny, in that you can take the key out while the ignition is still switched to on. The bike will even keep running if you don't kill the engine with the red switch. Anyways, the other day I turned the engine off, but pulled the key out in a haste before switching the electric off. I came out 6 hours later to find the ignition key in the on position and a bike that wouldn't start.

I got a fellow rider to give me a jump, and rode it around (seemingly not enough) to charge the battery. Parked it. Came back out 4 hours later. Still no juice. I had to let it sit for a few days while I was away.

Last night I got a few friends to come help me start the bike. First we tried jumper cables, with the car turned off, and nothing happened. It wouldn't switch over at all.

Then we push started the bike and she fired up after 3 attempts. This time I rode her around on the highway for about 40 minutes, keeping the RPM's between 4-6 or over.

I noticed that when I would accelerate, the speed and temperature lights would come on, but decelerating they would dim. It was night so that was very obvious. The same for the headlight and blinkers. I also noticed that the horn was considerably weaker. I kept riding until I noticed an improvement in the reaction time and quality of the sound of the horn. At that point I figured it was good enough. Literally pulled in, turned her off, and then out of curiosity tried to switch her back on. NOTHING.

Now I'm new to working on motorcycles, so bare with me if this seems obvious, but I'm thinking I need a new battery. For all I can tell, it's probably the original as it looks grey and old. This is even some slight corrosion happening at the positive pole.

I don't think it would be a problem with the electrical wires since we were able to push start the bike and trick it into charging. It seems that the break in the circuit loop is happening at the battery. Especially since it would not receive a jump the second time.

Any feedback would be greatly appreciated!! I'm looking to get this solved ASAP so that my lady and I can head to the beach this weekend.

Has anyone had luck buying batteries on Amazon?

MANY MANY THANKS!!
 

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Test the voltage at the battery at idle and at 3000 rpm.
At idle it should be getting apps 13.5 vdc and at 3000 or more it should be 14.5 vdc.
Anything less than that and you have a charging issue.
 

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First thing you will need to do is get (or if you have, use) a multimeter. You will need to measure the battery voltage when the bike is running. There is a good chance the battery is crap, but may also have a dead charging circuit. Measure the charging voltage, and if its less than 13.5V or over 14.5V then you have a problem. Now it sounds like the ignition switch has been bypassed (if it runs when turned to off) which means you will get the electrics on the bike sucking power from the battery when its just sitting there. The ignition switch breaks the main power feed to the bike (black wire and red if I remember correctly, best to check the diagram) which stops this drain when the bike is off and sitting.
 
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