1978 Honda CX500 Won’t Charge the Battery

I bought a 1978 Honda CX 500. The problem. The battery died on me when I rode the bike home. I put new spark plugs in the bike and a new battery. It started up and rode strong for 3 solid days of riding. However, when I went to Portland over the weekend I returned to the same problem. It won’t start. It sounds like it wants to, but it just won’t. So I have been told it is either the voltage regulator or the alternator. If it is the alternator, my manual says I have to take out the entire engine to replace it. Would it be incredibly costly to have this work done for me?

I’m a bit lost at the moment. If the voltage regulator doesn’t fix the problem.

Thanks a lot for your help.

Sounds like your alternator to me. The CX500’s and CX650’s are famous for their alternators going out. It is by far the biggest weakness of those bikes. Everyone who owns one will eventually have to replace the alternator.

The alternator is on the rear of the motor, and because of it’s location it tends to get very hot. Over time the excess heat will kill it.

Weak output is the biggest symptom, and it will get progressively worse. As you ride your battery is draining and not being recharged.

I would encourage you to tackle the project yourself. You’ll be paying big bucks for a shop to do it because of the age of the bike and the labor involved. You will have drop the motor from the frame – however, the CX500 motor is actually very simple to remove. Just undo a few bolts and it drops straight down.

Sorry for the bad luck. The CX500’s are great bikes and are worth repairing.


Alright man. Thanks for the advice. I’m gonna run with it. I’ll try to tackle this wild drunk donkey of a problem and ride the open road on that beautiful bike.

Thanks for the help.

Evan Fell

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