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Discussion Starter · #1 ·
Hi Guys,

I just picked my 1981 CX500E up from the shop after getting its road worth certificate done. Riding home I only made it 2km before I noticed a significant lack of power in 4th and 5th gear and then the bike stalled. I tried to restart the bike but didn't have enough battery to kick her over. Was successful in roll starting and jump starting her which will give me another km or so before the process repeats itself.

I'm hoping its just a battery that I need but sounds to me that I might need to replace the alternator/stator?

Prior to leaving her with the mechanic she ran fine without faltering. I spoke to them and they wiped their hands of it saying they didn't touch the engine, they only rewired the brake lights and changed the tyres.

Thoughts would be appreciated! Going to try it with my brother's battery to see if I can diagnose it tonight.

LeeDee
 

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I'm hoping its just a battery that I need but sounds to me that I might need to replace the alternator/stator? Going to try it with my brother's battery to see if I can diagnose it tonight.
That sounds the best bet. Don't do anything drastic until you've at least proved the battery's not causing the problem. If the battery's too low on power to start the bike, it does sound like a failing battery is the problem, but once you try your brother's battery you'll need to check it's charging OK.
 

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'84 CX650E that is evolving into a GL500
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Does your bike still have a vacuum petcock? If so, make sure that the vacuum and drain/vent lines are connected correctly. If they are reversed the vacuum valve won't open properly so it will run until the carbs empty, then stall out but will start again after a few minutes and do the same thing. Don't ask how I know about this :rolleyes:

As for the battery, they could have killed it by leaving the key on while they worked on the lights but if that was the case it probably wouldn't have started at their shop. It is also possible that the battery was just at the end of its life and the timing was co-incidental. I would start by giving the battery a good charge and then testing the charging system as described in the Factory Shop Manual (available from the Wiki - link in my signature).
 

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Discussion Starter · #4 ·
Update: Got my brother's battery into it and she started beautifully and idled without an issue for 10 minutes.

His battery is brand new however and I am wondering if the charging system is not working and rather if it might have been the strength of his battery keeping her going for that period? Is this likely?

I will get onto testing the system tomorrow, I need to get the right equipment to do so.

Thanks for your helps guys!
 

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All you'l be needing is a multimeter to do the testing. IIRC, you need to rev it to 5k, hold it there and put the sensors on the positive and negative terminals on the battery. The readings should be in the 14v range(please correct me if I'm wrong).
 

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That's pretty right. Test it on the 20 volt scale at idle 2k and 4k. Should top out around 14.5 volts.

Your bike should continue to run once started as it should be CDI. Battery power should have no effect.

You may have a rat in the works.
 

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That's pretty right. Test it on the 20 volt scale at idle 2k and 4k. Should top out around 14.5 volts.

Your bike should continue to run once started as it should be CDI. Battery power should have no effect.

You may have a rat in the works.
You may well be right. I was wondering that myself anyway, but LeeDee says it's a 1981 CX500E, which I don't think is right really. Avatar shows it may be a B (did you get those in Oz?) Perhaps LeeDee thinks it's an E because the engine has CX500E in its number?
 

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Discussion Starter · #8 ·
You may well be right. I was wondering that myself anyway, but LeeDee says it's a 1981 CX500E, which I don't think is right really. Avatar shows it may be a B (did you get those in Oz?) Perhaps LeeDee thinks it's an E because the engine has CX500E in its number?
I only say 'E' because it has CX500E on the engine and the engine matches the frame? I'm not overly familiar with the models and their regions but would it make a difference to my situation?
Off to by a multimeter to test her out.
 

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Either the first few digits of the engine number or a pic of what's under your seat should clear up any confusion.

From info supplied I'm ASSuming the bike is an 81 with CDI.

Though from the symptom {won't stay running with battery not charging} does suggest the bike may be TI ignition.
 

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From the WIKI - How the CX GL came into being

But that isn't as complete as it might be, with only a passing reference to the CX/GL400 models and nothing about the Eurosports. The 1981/2 CX500E & 1983/4 CX650E were the normally aspirated lay-down-on-the-tank sport bike version (they also had very sporting Turbos). They have the Pro-Link monoshock rear suspension, Transistorized Ignition, vacuum petcock and very sporting (for the time) styling, including a seat that wraps around the rear of the tank.

IT2J6579-01.jpg

You will notice that the side cover says "CX500 Sports", not "CX500E" The only place that the actual complete model number appears is on the builder's plate attached to the steering head, which also includes the model year and the date it was built.

The engine numbers do not match the frame numbers. For reasons known only to the people working at Honda all those years ago the '78 & '79 engines have a CX500E prefix while later engine numbers do not include the model number.
Serial Numbers - CXGL

If you are talking about the bike in your avatar pic it is not a CX500E. Part of what all of that means is that it does not have a vacuum petcock so you can ignore what I said about that.
 

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Discussion Starter · #12 ·
Thanks for all the responses guys.

So the engine number starts CX500E2402***.

Today while feeling particularly optimistic, I hooked the old (? faulty) battery back up and jump started her without an issue. To my surprise she idled for a solid 10 minutes without a problem. I took her for a spin for about 30 minutes in which time I turned her off and then immediately back on again successfully. After a quick trip home I turned her off and then tried to start her again however this time had no luck - very low power and only a very pathetic attempt to kick over.

I also got my hands on a multimeter which reads 12V while revving at 2500RPM so I'm hoping this means my stator is ok and the battery is the issue?

So thats where I stand at the moment. I now don't have the opportunity to use a second battery to see if my bike will run it down. Should I just bite the bullet and buy a new battery and see how it goes in the bike or is that premature?

Cheers again.
 

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Engine number is an 82 engine. It should be TI ignition and this fits with the bikes symptoms, though I would think it should run for longer than 10 minutes on a battery that will start it... or was it a jump?

Your bike isn't charging. Even for a standing battery the voltage should be 12.5 to 12.7. 12 is flat.

At 2.5k revs you should be showing a charge... say 13+, probably higher.

What does the plug under the seat look like as they can be cooked by the voltage.

While theretest the three pins on the engine side of the plug with meter set on the low ohms scale. All 3 pins should have low and even resistence. Then check all 3 pins to earth. This should be open circuit, otherwise the stator is shagged.

If it passes this the problem could well just be the battery... you can't charge the unchargable. But if it can start the bike it's likely not that far gone.
 

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Not to be discouraging, but 12V at 2500RPM is way low and suggests that your stator's charging coils are kaput. There's a test you can do with the ohmmeter function of your multimeter - unplug the connector with three yellow wires coming from the stator and read the resistance from each of those wires to ground. It should be infinite (i.e. no connectivity to ground.) I would definitely hold off on buying a new battery until you check this out.
 

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Full circle. He's CDI.

The stator is stuffed as it's not charging the battery. You have two choices, either another CDI stator that should be available at David Silvers Or a later and cheaper 'charge only' stator and either an ignitech or Raesan ignition unit.

But I am wondering why your bike doesn't want to stay running. Could you test pin 9 on this chart for continuity to the three yellow charge wires?



Or it could be a dirty killswitch.

By the way, your airbox intake snorkel is backwards.
 

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Discussion Starter · #18 ·
Hmmm not good.

I have a second engine that came with the bike so will have to pull that apart and hope that stator is better than the one I have. If not and I have to order it any chance anyone knows the part number?

Did we come to a consensus on what year model my bike/engine is?

Thanks again guys.
 

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Discussion Starter · #19 ·
P.s. will do the check on the 9 pin and spin the airbox snorkel around.
 

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