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1982 honda cx500c
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Discussion Starter · #1 ·
Hello, new to the group but have learned so much reading over past posts. I have a 82 cx500c that ran when I started this adventure, I drove it everything sounded and worked as it should. I replaced the gasket behind the fan on the front end, carb rebuild, and replaced the vacuum petcock and fuel lines. I also took the starter/kill switch apart and cleaned and relubed everything. New spark plugs. It's trying to crank over and sounds like it's going to fire but when I release the starter it just dies. I have spark at both plugs and fuel in the bowls steady stream out the drain. Re gapped the valve clearance. Checked the fuses and tried starter fluid. Still nothing. Was going to try to bypass the vacuum petcock and a few other things. Any suggestions? Thank you guys!
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Welcome, RamRod!
You've got spark at the plugs and fuel in the bowls, but not necessarily getting to the cylinders. My suspicion immediately falls on the "carb rebuild." Can you describe your procedure in detail?
 

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1982 honda cx500c
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Discussion Starter · #3 ·
I ordered a rebuild kit off ebay. I'll try to post the picture of the kit. There were a few extra o rings and 2 tiny metal washers that were leftover. I took everything apart cleaned everything and replaced as I went. I did just notice fuel leaking from the accelerator pump so I'm going to pull them back off and see if I missed something.
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Just use the rubber from that kit and clean and reuse your original brass.

Try the old ACVs.

Some of the parts in these kits aren't fit for purpose and can give a number of issues. The emulsion tubes and mixture screws don't meter properly and the mixture screws have a disturbing habit of breaking their tips off in the carb leading to endless hours of mirth and merriment and sometimes forcing the acqisition of new carb bodies., float needles give incorrect fuel levels and the ACVs can actually work backwards - leaning the mix when it should be enrichening.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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The two tiny metal washers go next to the two tiny o-rings on the idle mixture needles. The originals might still be in the holes, probably with the old o-rings.
As above, reuse your old brass. Check that the mixture needles haven't broken off in the orifices. Not uncommon with aftermarket parts, and would keep gas from the idle circuits.
Did you remove and clean the emulsion tubes? Just spraying cleaner through the carbs isn't really cleaning them. All the little bits need to be removed and scrubbed.
I don't recall whether the '82 Custom has threaded or pressed-in idle tubes. In the former case, you'll need the appropriate screwdriver (and maybe some heat and penetrant) to remove them without mauling the brass. In the latter case, there are a couple ways to pull them out. A #1 fluted bolt extractor works, with a good bit of held breath and apprehension. Tapping the end the tube to draw out using a small bolt, nut, and washer is safer, though I haven't tried it yet. There are other threads here with more detail on that.
 

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Should be threaded in idle jets by 82 if the carbs are the original set.

The bike should actually be able to start without the carbs fitted to rule the carbs out.

I was recently running one - just to see if it would start - by spraying a short burst of brake cleaner straight into the head ports.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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I don't know if the threaded tubes started with the GL500, or with the move the TI. I suppose I could look in the appendices in the FSM, or maybe Larry's carb bible.
 

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Based on my experience I believe the threaded idle jets started on CX models in 80. Not certain but about 1/3 of the sets I see are threaded.

I see I typed pressed in the post above when I meant threaded. Edited now.
 

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1982 honda cx500c
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Discussion Starter · #9 ·
OK awesome thank you guys! I'll pull the carbs and put the old brass in after I scrub them. I'm not sure about the idle tubes. The 2 cross tubes are press in with a o rings on the end. I'm going to be working on it all this week I'll keep you posted! Appreciate all the help!
 

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The tubes with O rings on either end are main fuel and accel pump transfers.

The idle jets are within the carbs.

Automotive tire Bicycle part Eyewear Wood Automotive wheel system


Idle under rubber plug.
 

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1982 honda cx500c
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Discussion Starter · #11 ·
OK yeah those thread in. Looking at it now I think where I screwed up is the mixture jet. The manual says don't remove or adjust. That's the part I changed that sticks out farther with the new piece. I did adjust it to the 1.5 turn that it says for this bike.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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Does it recede from the venturi when you back it out?
 
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1982 honda cx500c
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Discussion Starter · #13 ·
Automotive fuel system Gas Auto part Metal Composite material
the old one was receded in that hole. The new one has that longer brass end on it. I'm sorry not really familiar with all the different parts. My uncle has been helping me. He's coming back on Wednesday, I'm going to run all this by him.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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I meant does the tip withdraw from the inside of the carburetor when you back off the screw? Some of the aftermarket mixture needles don't fit the taper in the orifice correctly, and they can break off if seated too firmly. If that happens, you won't get any fuel at idle.
 

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'84 CX650E that is evolving into a GL500
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Before you go too far, this line in your original post caught my eye
replaced the vacuum petcock and fuel lines
Did you replace it with a vacuum or non vacuum type? If it is a vacuum type you will need to fill the float bowls before the engine will start. That can be accomplished several ways (my favourite is disconnecting the fuel line from the petcock, adding a small funnel and pouring in 90cc of fuel but some prefer to blow into the end of the drain/vent hose that connects to the small hose barb that is closest to the main body of the petcock and hangs below the bike).
And speaking of the small hose barbs, it is very easy to mix those small hoses up. The vacuum line (from the left side of the right hand carb) should be connected to the barb farthest from the main body of the petcock.

Welcome to the forum 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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1982 honda cx500c
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Discussion Starter · #18 ·
It is a new vacuum petcock, I think I have the lines right. There was fuel when I drained the bowls after trying to start it. I'm still not finding where those small washers go. I pulled that rubber boot and unscrewed the fitting under it but the washer doesn't fit around that piece. There's the 3 barbs on the petcock, the large is supply line to the cross tube. The one in the center of the circle is the vacuum and the one small one in between those is drain correct? I'll post pictures of the spot I tried those washers.
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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