Electrical Questions/CX500 or any late 70s/early 80s Honda

[DenverDude2002]

Hi all,

my dad got a 1978 Honda CX500 with 9k this weekend. We're trying to get it road worthy and it seems the stator isnt working correcly. the exact problem is we're concerned its not charging. Its putting about 7 volts back into the battery, which doesnt seem high enough. Anyone have any idea what typical charge should be for a CX500 or any other Honda twin as a ref we could go by? WIf that staor is bad is it possible to get it replaced/rebuilt or what.

thanks for any help.

[angrypeppers]

DenverDude,

Can't help with the charging numbers...but check all of your grounds. May just be a little bit o'corrosion somewhere. There's at least a couple of CX500 owners here, hopefully they can help out with bike-specific suggestions.

Thx!
Chris

[Kal]

Having a similar issue with our CX trike.

The battery on it really dos not seem to want to charge. I'm getting enough to get by on as long as I don't try to start it too often between journeys.

Suggestion from my local bike shop is the regulator/rectifier under the tank. It should have three wires leading off of it and all three when cross connected to a headlight bulb in pairs should make the builb real bright.

The other two options are a less bright glow, or completely dead. In either of these cases it's either got a problem with the reg/rec or the alternator.

Our CX did not want to start at all before the Battery, new leads and plugs were fitted - alon with a round cylander - can't remember what that was. Now there is just a bit of a knack to it.

[MotoF150]

The old 70's Honda's are noted for bad stators, check it for opens, shorts and grounds on the Rx1 setting of a vom meter, the last time I priced one they were $169

[ZooTech]

If you need a new stator, I have a semi-complete 1978 CX500 engine sitting in my garage. Before one of the exhaust valves broke, the electrical system was in perfect shape. Send me a PM if interested.

[koconno2]

Hey Denver Dude, I may be able to help if you’re still following this string. I’m guessing your in for a major repair if your CX has charging system failures like my bike and many, many other CX style engines.

I had the same symptoms as you when I first bought my 81 Honda CX650. I had no idea what a pain it is to work on this engine. First off, I wasted money on new rectifiers and spent hours chasing down all the grounds only to find out the stator was shot. But what killed the stator?

As you may know by now the CX engines have a very poor mechanical water pump seal design. When this fails, and it will, it allows coolant to seep into the crank case oil. The alternator assembly is hidden away in the back case of the engine and is bathed in oil when running. Eventually the oil becomes too contaminated with coolant and the alternator shorts out.

So, now you have two repairs on hand, which both require the removal of the engine from the bike. You can find all the parts on-line and if your lucky they might fit correctly. I currently have my CX650 in pieces waiting to get the rear engine case back from the machine shop. I had to have the bore for the water pump shaft seal enlarged because the only available seal is too large, which is not uncommon.

Good luck!