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1979 Honda CX500 Deluxe (US)
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Discussion Starter · #1 ·
So I picked up a '79 CX500 Deluxe cafe racer from someone two days ago. They stated battery would need replacing, but past that no issues. I go, pick it up, and get it jumped and ride 2 hours back.
Next day I go and go for a new battery, bike won't even turn over when jumped, so we jumped the starter solenoid and fired it up and rolled it in. Replace the battery, and the starter solenoid, and everything works fine for ~3-5 ignition cycles. Then now I'm stuck having the same issue, except the battery is the least of my worries. Before the new battery, the headlight and brake light assembly wouldn't even turn on, the only difference between the two batteries is that with the new battery, the lights stay on, only dim on push of the starter button.

The wiring on the bike is a rat's nest, but looking from under the seat, none of the fuses are blown, not even in the fusebox in the handlebars. One weird thing that happened was the taillight wire box (don't know how to explain it) but the little rectangular wire conjunction with weather stripping was loose when I first got the bike, I briefly wiped dirt and everything off, and got it somewhat clean so there would be solid contact, made sure that it clicked back in place, and then the bike started right up. But after I shut it off, I have had to jump the starter solenoid every time to get it to start. And as it's a daily driver kind of thing, I'd like to make this thing reliable, at least starting wise.

If y'all have any help, it would be greatly appreciated.
 

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Welcome to the forum. Visit the wiki, link in my signature line, and download a copy of the factory service manual for your particular bike. Check the service manual for the troubleshooting section.

It would help if we knew on what model of CX/GL your bike is based.
 

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1983 cx650c
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From your description of the "rats nest" condition of the wiring my suggestion it to get a volt/ohm meter, a decent wiring diagram, fully charge the new battery, and start checking the circuits. First place to start is output from the stator, then regulator rectifier,, then all grounds that are existing and see if any were eliminated as the circuits need them to work. It may take awhile and some repairs will probably be necessary. The previous owner may not have been honest about the condition of the bike. Patience and thorough examination of all circuits is required to sort out others oversights. There are threads to search on when an obvious problem is found. I hope the stator is intact as it is a job to replace. Good luck, there are more competent wiring specialists on here to answer specific questions about your bike. There are differences between models.
 

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1979 Honda CX500 Deluxe (US)
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63 Posts
Discussion Starter · #4 ·
So it's a 1979 CX500-D US version. The good is that the motor was just rebuilt and has all new gaskets. I went ahead and downloaded the service manual based off looking around other posts, and I'm reading through it now. I do need to pick up a volt meter regardless, so it won't be a bad start, but guess this will be my weekend project xD At some point I would like to re-wire the entire bike, this way I know for a fact things are what they appear to be, but with no previous knowledge, it can be a daunting task. When I was replacing the battery and starter solenoid, the assistant and I went through the entire system (he supposedly has had his fair share of CX's), and we went through all the basic wires for the ignition system, and they all reading what they "should"? But we even took apart the throttle box and cleaned the starter button connectors (had a little dirt and grime in there, but wasn't too bad) Believe me when I say I've already spent 5 hours wondering what the fuck is happening with the electrical. But to get started I'll grab a volt-meter tomorrow and over the weekend I'll start testing and seeing where the issue might lie.
 

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1983 cx650c
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Sounds like a good start. A can of contact cleaner is great for the plug in connections. From personal experience and reports of others, wiring can be frustrating. It's methodical examination and cleaning the old, corroded connections that results in successful repairs. I unplug and clean everything on old bikes as a maintenance operation.
 

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1979 Honda CX500 Deluxe (US)
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Discussion Starter · #6 ·
Sounds like a good start. A can of contact cleaner is great for the plug in connections. From personal experience and reports of others, wiring can be frustrating. It's methodical examination and cleaning the old, corroded connections that results in successful repairs. I unplug and clean everything on old bikes as a maintenance operation.
Might not make for the most "entertaining" day so to speak, but I'll definitely give that a shot first. I'm also going to call a shop tomorrow and see if he has anything to offer. I appreciate the help!
And how "fine" is it to just bypass the starter solenoid and have the bike fire up like that? Because I've done it today, and if it causes excessive wear to the solenoid, I'd rather know so I'm not buyin solenoids left and right 馃槄
 

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1983 cx650c
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A test jump start like that just eliminates the internal contacts so probably no problem. Grounds on old bikes are notoriously problematic so clean em all. The female part of the old bullet connectors gets loose and can be carefully squeezed with needle nose pliers to get better connections. Carefully inspect the stator connections,, it's the three yellow wires to the reg/rec and any corrosion is bad, melting of insulation worse.
 

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1983 cx650c
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When stator is unplugged there are two tests I think,, study that section of manual carefully as the stator and reg/rec are the heart of the charging system. Since the bike runs the ignition works, keeping it running requires a good charging system.
 

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1983 cx650c
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Remember to fully charge the battery,, even new batteries need charged, and periodically after. These bikes produce marginal charging current at best and a charged battery will start em when slightly discharged won't.
 

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1979 Honda CX500 Deluxe (US)
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Discussion Starter · #10 ·
Remember to fully charge the battery,, even new batteries need charged, and periodically after. These bikes produce marginal charging current at best and a charged battery will start em when slightly discharged won't.
You got it, I'll pick up a small battery charger as well then and have it checked. I'm slowly learning everything I can, and eventually this bike will be entirely redone, but for now I gotta make do with what I got, and learn and make the corrections as I go. I really appreciate the help!
 

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1983 cx650c
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Sorry if I'm blathering on,, I had tons of electrical problems to sort out also during the resto of the cx650. Patience and perseverance,,,馃槉
 

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1979 Honda CX500 Deluxe (US)
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Discussion Starter · #13 ·
Sorry if I'm blathering on,, I had tons of electrical problems to sort out also during the resto of the cx650. Patience and perseverance,,,馃槉
Haha, your "blathering" is giving me insight on where to start, so I'll take what I can get!
 

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1983 cx650c
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And avoid taking it to even a good shop if at all possible. The fun and satisfaction of learning and fixing it yourself is worth it,,, and shop rates take away the fun quickly.
 

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1979 Honda CX500 Deluxe (US)
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Discussion Starter · #16 ·
Is the neutral light on? Try pulling the clutch lever when you press the start button.
Here's the thing, I have no tachometers or anything. My phone is my speedo, and I have to shift by ear. Me being me, I haven't pushed the bike hard because I don't want to push past redline on accident, but in the future I might rewire the bike so that I can either have a digital interface, or just replace it so that I can at least have a tachometer.
 

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Be more worried about the engines operating temperature than exceeding the redline. Get some sort of temperature gauge. These engines do not like being overheated.
 

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1979 Honda CX500 Deluxe (US)
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Discussion Starter · #19 ·
Be more worried about the engines operating temperature than exceeding the redline. Get some sort of temperature gauge. These engines do not like being overheated.
What kind of temperature gauge could I get? I'm new to the entire concept, but I think I saw one where it replaces the dipstick?
 

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One that replaces the dipstick would read oil temperature, you want a coolant temperature gauge. Any 12 volt automotive temperature gauge will work although an adapter will be required for the sending unit. If you sourced the OEM tachometer for your bike it would include a temperature gauge. For that option you may need to fit the 7 volt regulator which may have been eliminated from the wiring harness by the previous owner.
 
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