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Discussion Starter #1
Hey guys,

1979 CX 500 here. Got it a few years ago and got it running as a proof of concept. Ran great back then with all stock parts. Have now done a great deal to it - pods vs airbox, mUnit Blue vs analog electrical, straight pipe with baffle out of H box vs cones. I’ve cleaned the carbs many many times to no avail, not even a change checked valve gaps and cam chain tensioner no dice.

Take a listen and see if you guys have any ideas? Also, I’m not a gear head in any way and clearly got too big for my britches here before realizing wtf I was doing. In that vein, anyone know any shops in the DC/DMV area that would work on a bike like this? It’s been 3 years of tinkering off and on and I’m just ready to ride.

 

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1981 Honda CX500C
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Hey guys,

1979 CX 500 here. Got it a few years ago and got it running as a proof of concept. Ran great back then with all stock parts. Have now done a great deal to it - pods vs airbox, mUnit Blue vs analog electrical, straight pipe with baffle out of H box vs cones. I’ve cleaned the carbs many many times to no avail, not even a change checked valve gaps and cam chain tensioner no dice.

Take a listen and see if you guys have any ideas? Also, I’m not a gear head in any way and clearly got too big for my britches here before realizing wtf I was doing. In that vein, anyone know any shops in the DC/DMV area that would work on a bike like this? It’s been 3 years of tinkering off and on and I’m just ready to ride.


The pod filters i belive you have to re jet. Take a look at Murray's Carbs or look up the right spec. I believe this is your problem.
 

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Discussion Starter #4
The pod filters i belive you have to re jet. Take a look at Murray's Carbs or look up the right spec. I believe this is your problem.
Do you happen to know if there’s a good set of jets that I could get and experiment? Are all jets the same thread/diameter, etc?
 

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Discussion Starter #7
Let me think on it.

Most use 90/120 jetti9ng with pods. But stock jets with pods shouldn't cause this.

What ignition system are you running?
I haven’t changed anything on the ignition system other than getting new plugs. Original MCU, etc.
 

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'84 CX650E that is evolving into a GL500
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BTW: 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 the Previous Owners may or may not have done 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).

The best advice anyone can give you about customizing any vehicle is to get it safe & reliable in more or less original condition and use it for a while before you start making any changes so it can tell you what changes it needs to make it do what you want/need better, then make the changes one at a time so you can change back if it doesn't do what you hoped it would. That approach almost always results in something you actually want to keep and use but making changes based on style or on what someone else (who may or may not really understand how the changes affect the way it works) has done often results in a piece of expensive yard art that you can't stand sitting on for more than a few minutes and might even be dangerous.
 

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Discussion Starter #14
BTW: 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 the Previous Owners may or may not have done 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).

The best advice anyone can give you about customizing any vehicle is to get it safe & reliable in more or less original condition and use it for a while before you start making any changes so it can tell you what changes it needs to make it do what you want/need better, then make the changes one at a time so you can change back if it doesn't do what you hoped it would. That approach almost always results in something you actually want to keep and use but making changes based on style or on what someone else (who may or may not really understand how the changes affect the way it works) has done often results in a piece of expensive yard art that you can't stand sitting on for more than a few minutes and might even be dangerous.
Could’ve used a lot of that advice about 3 years ago. 😅. Thanks for the wonderful welcome and the help already!
 

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Discussion Starter #16
Touché sir. Touché. And I appreciate any help or understanding that’s out there!
 

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Because you have changed so much from original , identifying the actual cause will not be easy. Changing jets will not fix much - the motor should run through the range - albeit badly all the way up. I would suspect a fault in your electrical/ignition system before anything else.
 

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Do you happen to know if there’s a good set of jets that I could get and experiment? Are all jets the same thread/diameter, etc?
From Murray's Carbs,
"90 and 120 mains


you can get them from jets r us on line



the carbs have to be removed and the bowls taken off to get to the jets then it is not hard"
Do you happen to know if there’s a good set of jets that I could get and experiment? Are all jets the same thread/diameter, etc?
 

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Discussion Starter #20
Took longer than the weekend to get back to the shop. Here is my findings. Not sure about the 7-5 read or the 9-5 read. So I changes some settings on the meter and it was giving kili ohms and mega ohms.

Thoughts? Thanks again for the help everyone!

Run through this on 2K ohms and give us your numbers.

View attachment 206725
Will do this weekend and keep you posted!
207083
 
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