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Discussion Starter · #1 ·
hi all,

long time reader, first time user of this forum. really appreciate all of the great info here.



my 81 gl500 (30k miles) ran flawlessly for the first year and a half that i owned it. it had been tuned up by a local shop and was 100% reliable.



last summer it broke down on me mid-ride and had to be trailered home. (bogging down when throttle is applied and eventually sputtering and stalling out)



upon getting home i found that a mouse had stashed some junk in the airbox, i assumed this was the root of the problem, but have not gotten to the bottom of things as yet... thinking that there's more to the problem than dirty airbox/carb...



since then i have been trying to fix the problem myself off and on to no avail. i am moderately mechanical and have done the following:



cleaned airbox

changed air filter

remove and clean carbs

change fuel

cleaned petcock

changed spark plugs

changed spark plug wires

changed ignition coils (w/ salvaged coils)

checked and adjusted valve clearances



the bike starts right up, idles fine, but will bog down when throttle is turned.

a couple times the bike has acted like it was fixed (just to get my hopes up), then gone back to bogging down when throttled up.



just feel like the bike was SO reliable, and went bad SO quickly, there might be some stupid thing that i am missing, or forgetting, or just plain ignorant of.



not sure if this is unrelated or not.. but my tachometer has since stopped working as well.



love to hear any thoughts you all may have.

thanks so much

many blessings!

 

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Hi Neighbor,

Are you sure the vacuum petcock is working correctly?



If the hose that runs to the right side carb is cracked or loose fitting on either end it could cause your symptoms.



Also you can see this page at DaveF's website, he has very good and easy to follow troubleshooting procedures for the ignition system, also be sure to see the link on that page to the ground and main fuse page.



Hope this helps.
 

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Discussion Starter · #3 ·
hmmm since i have had the bike it appears that the petcock's two non-fuel line things are looped together with a small piece of rubber tube.



the right side carb has that part plugged with a piece of tubing and a machine screw stuffed down it.



i am glad to change either of these conditions if that might help, however to my knowledge these conditions were always like this since i have had the bike... which ran flawlessly for many moons.



could it be a timing thing perhaps?

when its running at idle, if i hit the throttle with a quick little twist it bogs immediately. if i rotate the throttle slower its not as bad, but it does eventually stumble and fuss.



grasping at straws now.

seeing lots about stators, but im not even sure an 81 gl500 has a stator?



i do also have a salvaged voltage regulator on hand.. dont know if that's worth throwing on the bike to see if it makes a difference.



hmmmm.

 

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hmmm since i have had the bike it appears that the petcock's two non-fuel line things are looped together with a small piece of rubber tube.



the right side carb has that part plugged with a piece of tubing and a machine screw stuffed down it.


Someone probably modded the petcock to work as a manual one.



If you are sure that you are getting a good supply of fuel from the carbs it should be ok.

You could try removing the fuel line from the carb and putting a piece of hose on the tap, stick the end in a clear bottle, open the petcock and see if fuel flows freely out.



Your bike has transistorized ignition so I don't think the stator would be a problem,,you do have a stator, but it does not power the ignition the way it does on a CDI bike, yours just charges the battery.



I don't think timing or voltage regulator would be the problem either.



I would suggest cleaning the carbs but you say you have done so already. They can be temperamental and can take a couple of tries sometimes. Did you soak them and blow high pressure air through all the passages?



Check the main fuse and the grounds as per the link I posted above.
 

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Someone probably modded the petcock to work as a manual one.



If you are sure that you are getting a good supply of fuel from the carbs it should be ok.

You could try removing the fuel line from the carb and putting a piece of hose on the tap, stick the end in a clear bottle, open the petcock and see if fuel flows freely out.



Your bike has transistorized ignition so I don't think the stator would be a problem,,you do have a stator, but it does not power the ignition the way it does on a CDI bike, yours just charges the battery.



I don't think timing or voltage regulator would be the problem either.



I would suggest cleaning the carbs but you say you have done so already. They can be temperamental and can take a couple of tries sometimes. Did you soak them and blow high pressure air through all the passages?



Check the main fuse and the grounds as per the link I posted above.
 

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mine does a similar thing. it runs great for a few miles then starts bogging down. noticed that my petcock vent hose is leaking gas. could it just be a petcock issue?
 

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Discussion Starter · #8 ·
the exhaust does not smell overly rich to me, but i suppose it could be too much fuel somehow.



i did not soak the entire carbs for any length of time as i did not have a bucket of carb cleaner. i did do my darnedest with multiple spraycans, but hey im sure soaking would be better. it runs so smoothly at idle that i kinda started to rule out the carbs, but maybe i am missing something in there.



does anyone have a good easy to follow tutorial or video online on a thorough carb cleaing for the gl? i do have the clymber book for this bike and have read it very closely, but perhaps i have missed something.



like i said i am somewhat mechanical, i do have a certain amount of trepidation when it comes to unscrewing every screw and jet in the carb and then not knowing how many turns or how tight to put things back together.




what the heck... the bike is doing me no good as is.... im ready to go for it at this point!


haha!
 

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Please take a few minutes to edit your signature to show your bike's year and model.



Have you performed the main fuse modification yet? Sometimes the symptoms of a bad original style main fuse can appear as if there is a carb problem.



What is the battery voltage when the bike is running?



You mentioned the right carb vacuum port was plugged with a hose and a machine screw. Is all of this air-tight with no leaks or splits where the hose is attached?



I also don't think you have a timing problem. If you did, it wouldn't run at idle. Not to mention it's nearly impossible for the timing to shift on its own.



Do you have good spark on both sides?



The symptoms sure sound like a carb problem, though.
 

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Discussion Starter · #10 ·
battery is getting checked out now. i will check on the voltage.

i will also check the condition of the plugged carb fitting



i really like the look of that main fuse mod. i will do that just for fun. looks like a big improvement on the original.



say whats the best way to check spark quality? i know they are sparking and the exhaust looks the same from both pipes from what i can tell....
 

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Discussion Starter · #11 ·
ok heres an update.

battery is ok,

changed out the main fuse with a slick rubber covered inline fuse holder from napa.

this may have helped some, ran well enough to go up and down the drive a few times... but there is still a problem persisting.



i am thinking at this point i should probably pull the carbs again and give em a more thorough cleaning.... thoughts?



any suggestions on a good tutorial that i can find online... again its an 81 gl500. am i going to need any special tools for this? sychronizing tool etc?



thanks guys
 

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Discussion Starter · #12 ·
oh also wanted to mention that since the first time i took the carbs off the idle seems a little low... meaning that i have to run the choke slightly pulled to get i nice smooth idle that will stay running... could that make for part of this bogging down when hitting the throttle, and running rough at higher rpms?
 

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oh also wanted to mention that since the first time i took the carbs off the idle seems a little low... meaning that i have to run the choke slightly pulled to get i nice smooth idle that will stay running... could that make for part of this bogging down when hitting the throttle, and running rough at higher rpms?


That is a symptom of the low speed idle circuit blocked/restricted.



Click here,



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=19&t=32



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=19&t=140
 

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Please take a few minutes to edit your signature to show your bike's year and model.



Have you performed the main fuse modification yet? Sometimes the symptoms of a bad original style main fuse can appear as if there is a carb problem.



What is the battery voltage when the bike is running?



You mentioned the right carb vacuum port was plugged with a hose and a machine screw. Is all of this air-tight with no leaks or splits where the hose is attached?



I also don't think you have a timing problem. If you did, it wouldn't run at idle. Not to mention it's nearly impossible for the timing to shift on its own.



Do you have good spark on both sides?



The symptoms sure sound like a carb problem, though.




Is the Fuse an issue with CX-Cs? It sounds like I'm having a lot of the same issues after washing the bike yesterday, but it happens to me after a short ride of no issue, then randomly it starts bogging down horribly. I'll see what I can figure out, maybe its a similar issue.
 

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Your bike is an 81 CX so it uses the CDI ignition. CDI ignitions are completely powered by the stator, so if your bike is bogging down the main fuse is not the culprit.



That said, it is still a good idea to perform the main fuse modification to eliminate other potential gremlins.



TI ignitions are powered by the battery so the main fuse can affect the ignition performance on bikes so equipped.
 

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Have you double checked to see that the jets are installed in the carbs in the right position. If the primary and secondary jets are reversed you will get a problem with the idle and it will bog when getting on the throttle.
 

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You also may want to try looking for an air leak allowing a much leaner mixture than needed when the throttles open. For instance, a vacuum leak around the intake boot of one side could allow air in. Some folks use an unlit propane torch, or some other combustible spray like carb cleaner. Sprayed sparingly around the carb and intake while you attempt to throttle up could provide extra fuel and indicate where a leak could be.
 
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