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Discussion Starter · #1 ·
My 1980 Honda cx500 custom has been a project I've been working on and I got it running and it's a joy to drive. However, I was going down the road at about 60 mi/hr and the engine just died.

Now when I start it (starts up great and sounds good) it revs up to 4000 rpm. Any advice would be greatly appreciated!

Thanks!
 

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'84 CX650E that is evolving into a GL500
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Welcome to the forum. Please add your location and your bike's model and model year to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).

And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and may or may not have had all of the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).
 

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1983 Honda GL650I Silver Wing Interstates (1 Red, 1 Gray)
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Following this post.

Once in a while my '83 GL650I revs to 4,000 RPM when starting for no apparent reason.

Thinking this has got to be part of the electronic ignition getting ready to die.

Will be curious if any one has some ideas on this to help out the OP.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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'84 CX650E that is evolving into a GL500
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When it happened to my 650 it turned out to be the shaft of the accelerator pump hanging up and preventing the throttle from closing. At first the occasionally wouldn't drop below about 2,000 RPM when I stopped at intersections but It got so bad that it eventually wouldn't go below about 3,000 at all. When I figured out what the problem was I cleaned up the corrosion on the shaft and lubed it with silicone grease and things went back to normal.

Mine didn't stop running while travelling at speed before it idled fast so Gatsby's problem is probably something else but it could be what's happening to Wingman's bike.
 

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1983 Honda GL650I Silver Wing Interstates (1 Red, 1 Gray)
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What's the rationale behind that claim?
Only happens when starting a cold engine, choke on.

Bike seems like it's running on one cylinder for a minute or less, then I hear a loud click like someone flipped on an electric switch, followed immediately by a jump from about 2K RPM to 4K RPM. Got to then push the choke back in half way to get cold idle back down to 2K. After all this drama the engine runs great with no issues.

Regarding the OP's shut off issue: What about disassembling and cleaning the engine stop switch? If that switch is barely making good contact to begin with, handlebar vibrations during riding could make it cut out just long enough to kill the engine.
 

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Regarding the OP's shut off issue: What about disassembling and cleaning the engine stop switch? If that switch is barely making good contact to begin with, handlebar vibrations during riding could make it cut out just long enough to kill the engine.
The OP's bike has CDI so the kill switch grounds the CDI when in the off position. Easiest test is to disconnect the black/white wire.

Gatsby77 after the engine died while riding were you able to restart the engine and continue the ride? If so was the high idle evident at that time or was it evident on a later start of the engine?
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Only happens when starting a cold engine, choke on.

Bike seems like it's running on one cylinder for a minute or less, then I hear a loud click like someone flipped on an electric switch, followed immediately by a jump from about 2K RPM to 4K RPM. Got to then push the choke back in half way to get cold idle back down to 2K. After all this drama the engine runs great with no issues..
Nothing in your description indicates a looming electrical failure. Electrical faults usually increase with heat, rather than decrease.
The rpm jumps up when the second cylinder begins to fire. Starting on one cylinder might result from a weak pulser or coil, but it's more likely a constricted idle jet on one side. My GL650 does the same on cold starts, but I haven't gone through the carbs yet.
I suspect the loud click is post ignition of unburned fuel in the top of the header. My 650 does that, too.
 

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1983 Honda GL650I Silver Wing Interstates (1 Red, 1 Gray)
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Nothing in your description indicates a looming electrical failure. Electrical faults usually increase with heat, rather than decrease.
The rpm jumps up when the second cylinder begins to fire. Starting on one cylinder might result from a weak pulser or coil, but it's more likely a constricted idle jet on one side. My GL650 does the same on cold starts, but I haven't gone through the carbs yet.
I suspect the loud click is post ignition of unturned fuel in the top of the header. My 650 does that, too.
I was actually including coils or ignition modules in my definition of "electrical fault". Poor choice of words on my part.

Can't be my carbs. I completely rebuilt them using an ultrasound cleaner and a Randakks Cycle Shack rebuild kit. Idle jets were cleaned and sized, set at 2&1/2 turns out. Been rebuilding carbs for decades. (Professionally, for pay, for quite a while as well, though not so much anymore now that I'm retired and "living the life of leisure". Hah! Right!) Hardest ones I ever did were the six carb bank from my friend's 1981 Honda CBX.

Been through most all of this stuff...

CX & GL Ignition Problems

and...

Main Fuse and Grounding

and still can't seem to find anything wrong.

I've got a spare ignition module/solenoid assembly. I'm tempted just to swap that whole thing out and see if anything changes just for the heck of it.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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I was actually including coils or ignition modules in my definition of "electrical fault".
What I was trying to say is that while I can't say definitively that it isn't a failing electrical component, I don't think that's your problem.
 
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1983 Honda GL650I Silver Wing Interstates (1 Red, 1 Gray)
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What I was trying to say is that while I can't say definitively that it isn't a failing electrical component, I don't think that's your problem.
What I was trying to say is that while I can't say definitively that it isn't a failing electrical component, I don't think that's your problem.
Just a side note:

I lived in Minneapolis from 1976 to 1984. My southern born and bred wife had enough of winter after eight years and said "I'm moving back south, you can come with me or not! I figured it wasn't really a choice!
 

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Try a run up the street with the air filter removed. Just in case.

Are you running stock CDI?
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Just a side note:

I lived in Minneapolis from 1976 to 1984. My southern born and bred wife had enough of winter after eight years and said "I'm moving back south, you can come with me or not! I figured it wasn't really a choice!
I grew up outside Baltimore, and fulfilled my mother's prediction that I would go away for college, meet a girl, and not come back.
 
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Hey Gatsby77, another thought on your cutting out problem.

When's the last time you took a good look at your main fuse? If you still have your original dog-bone style fuse, those things can fail intermittently if they're very old and starting to develop hairline cracks.

Take a close look at yours.
 

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Discussion Starter · #16 ·
The OP's bike has CDI so the kill switch grounds the CDI when in the off position. Easiest test is to disconnect the black/white wire.

Gatsby77 after the engine died while riding were you able to restart the engine and continue the ride? If so was the high idle evident at that time or was it evident on a later start of the engine?
After it had sat for a few hours it started back up. I rode it again (not as far as the time before) and I noticed the high idle for the first time when I was at a stop sign. When it dies it takes a couple hours before it will start again. Now the high idle happens whenever I turn it on.
 

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After it had sat for a few hours it started back up. I rode it again (not as far as the time before) and I noticed the high idle for the first time when I was at a stop sign. When it dies it takes a couple hours before it will start again. Now the high idle happens whenever I turn it on.
That makes me think that the two symptoms are not related but a evidence of two separate problems.

Do you have stock gauges on the bike? If so, any evidence of overheating?

Does your bike have stock CDI system? If so it may be a good idea to check the resistance on the stator and pick ups and advancer coils both cold and hot. Same goes for the ignition coils.
 
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Nothing in your description indicates a looming electrical failure. Electrical faults usually increase with heat, rather than decrease.
The rpm jumps up when the second cylinder begins to fire. Starting on one cylinder might result from a weak pulser or coil, but it's more likely a constricted idle jet on one side. My GL650 does the same on cold starts, but I haven't gone through the carbs yet.
I suspect the loud click is post ignition of unburned fuel in the top of the header. My 650 does that, too.
I confirm the "click" when second cylinder comes on line. I've assumed it was an exhaust backfire from lean mixture. I've heard it from bikes with clogged fuel line to one carb. My '81 GL has done that every cold start for 15 years.
 

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Discussion Starter · #19 ·
Everyone, I apologize for the delayed response. I got the bike up and running and the original problems have been fixed! Sorry to say that I'm not sure what the exact solution to the problem was. But thank you all for the advice.

I do have a more recent problem with the carbs. Right before going on a ride, I turned the fuel to "on" only to have fuel start leaking out of the carbs.
Musical instrument Automotive tire Automotive exhaust Wind instrument Rim

Motor vehicle Automotive tire Automotive design Automotive exterior Auto part


I only just started removing it and decided to take a picture and see if anyone has any advice before I went too crazy.
Automotive tire Motor vehicle Hood Gas Auto part

Here's another picture.

Any help would be appreciated! Thank you all in advance!
 

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Your float needle valve is not sealing properly. Your overflow tube and drain may also be blocked as fuel should not rise to the level of the vent tube.
Try to flush the needle valve and seat by turning off the petcock and draining the float bowl. then turn on the petcock. The in rush of fuel may clear debris.
If the float is stuck tapping the float bowl may free it.
 
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