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1979 CX500 2104640
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Discussion Starter · #1 ·
After sitting for 11 years, I'm hoping to get this guy going again (pic is from 2003). It last was running on the left cylinder only and I have a new ignition pulser so hopefully that's the ticket. Supposed to get a tropical storm coming through central FL this weekend so I hope to get some engine cracking time in.
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I wish you well on your MC repair journey, nice looking bike!
 
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Hope is a 4 letter word when it comes to fixing things. Make sure the diagnostics back up your hypothesis. Ask me how I know. :)
Otherwise good luck, and the forum is here if needed.
 
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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 the Previous Owners may or may not have done the maintenance necessary to keep it safe & reliable (not to mention the problem you know about and whatever has deteriorated while it was in storage) 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. I'd tell you to 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) but you already know they are well past that age. If your bike still has the original rubber brake line (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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Welcome, enjoy the CX experience-did the bike store well? Any newer pics of the bike...did you store it yourself years ago, thats you in the OP in the 2003 pic?
 

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1979 CX500 2104640
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Discussion Starter · #6 ·
Welcome, enjoy the CX experience-did the bike store well? Any newer pics of the bike...did you store it yourself years ago, thats you in the OP in the 2003 pic?
Hi Bahn, yes that's me back in college at SIUE there in that 2003 picture. I rode the CX500 a lot to and from a different community college before that. My first wife bought me this bike while we were dating for around $800 US. I've already replaced the stator once a long time ago after finding the battery wouldn't stay charged but I could push start it and it would still run. I got a good deal on the stator but I had to crack open a donor bike engine and of course my own to do the swap. The right cylinder went out around 2010 or so and I've kept it inside in a garage in Indiana except the last year needed space and moved it out to a storage shed in the back yard. It's developed some surface rust but I haven't tried cleaning it off yet. The seat is in good shape and the tank is but I have the tank down to primer and needs painted.

Would this be an ok thread to post pictures and ask questions as I go?
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'84 CX650E that is evolving into a GL500
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You can ask questions here or start new topics for them, your choice.

Did you drain the tank and the carbs before storage? If not you may have a fun job ahead cleaning out the dried up fuel... (if that's the case you should probably do that before you paint the tank)

I think I'd want to get it running before I started putting effort into making it look better too. Have you figured out what the problem with the right cylinder is?

BTW: Don't forget to fill in your profile like I mentioned in post #4.
 

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1979 CX500 2104640
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Discussion Starter · #8 ·

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'84 CX650E that is evolving into a GL500
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I don't know enough about CDI to say for sure but that could be the problem (I'm sure someone who does know will let us know).
If it is you will need to either replace the stator or change to one of the modern electronic ignition systems such as Rae-San or Ignitech.
 

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1978 CX500 "The Grub", '83 GL650, '82 GL500 Project "AdventureWing", '79 CX500C, '78 CX500 Scrambler
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Some aftermarket stators have slightly different specs, so you might be OK there. I'd suggest you get it rideable and see how it behaves.
A failing pin 8 will manifest as a loss of power above 4 or 5k rpm. You could replace the stator again, or fit an Ignitech or Rae-san ignition module to bypass that part of the stator (they draw 12v from the battery, instead.)
I went with the Ignitech when mine failed several years ago, and I've since fitted a less expensive G8 (GL500) stator, since I no longer need the ignition side.
 

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Discussion Starter · #11 ·
This is weird. I just bought a new battery and charged it some and gave the start button a push with charger still hooked up to the battery. Both spark plugs were arcing while i had them against the cylinder heads on the outside of the engine. Wasn't expecting to get anything at all out of that right side. I don't know what's changed between now and the last time I worked on this thing so many years ago 🤦‍♂️.

I have a couple carb kits so that will be next to get them installed and see what happens ;).
 

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1979 CX500 2104640
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Discussion Starter · #13 ·
Carbs cleaned last night, best I could do. Used the old brass and float valves as suggested. The float valve height adjustment wasn't clear to me from the service manual. But at the open position the float is pulling the needle open and at the closed position (float all the way up) there is still a small length of travel for the spring pin that's part of the needle but very close to bottoming out. I set the float height assuming the spec from the service manual to mean that 0.61" is where the needle should first close and the float tab start contacting the needle spring pin. As the float rises further it is compressing the needle spring. I had goofed with the carbs and tried cleaning them before but didn't have the gaskets and o-rings to put it back together properly like I do this time. Might as well do the cam chain tension adjustment while there's room with the carbs off.
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Might as well do the cam chain tension adjustment while there's room with the carbs off.
You don't need the carbs out to reach the cam chain adjuster. That should be done at every oil change, along with the valve adjustments.
 

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'84 CX650E that is evolving into a GL500
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I set the float height assuming the spec from the service manual to mean that 0.61" is where the needle should first close and the float tab start contacting the needle spring pin.
That is correct.

The carbs shouldn't interfere with getting at the tensioner adjuster bolt.
 

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Discussion Starter · #16 ·
it fires but only runs with the choke on @ 2K RPM. I can hit the throttle a few times and RPM increases briefly but then backfires a little and bogs down and then back to 1K ~2k RPM. Doesn't run at all with choke off. Not getting enough fuel? This running state is back where I started before giving up the first time and storing it. Both cylinders and exhaust off the cylinders are getting hot so it doesn't appear like it is firing on one side only. Any suggestions?
 

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Discussion Starter · #18 ·
Hey nolimitz, I haven't replaced the big o-rings on the manifold tubes yet but ordered Larry's book just now. I tore one of the rubber tubes that connects to the air filter box so was testing the engine running without connection to the air filter box. As far as vac leaks, I'm not understanding what else you are referring to. There looks to be a small nipple on each carb - are those for hooking up sync pressure gauges? Should those have a cap on them when not syncing?

Bob, I read a little about the rae-san system and how it deletes some of the coils. That sounds like a good idea. Can you provide a little more background on the charging stator though? Is there a brand new option? I am still running with a junk-yard stator right now and it isn't aftermarket. Some part #'s of the equipment I should get would be helpful

Thanks for helping me.

PS during the engine running yesterday I aslo could hold RPM's around 7K again with choke all the way on and not dying.
 

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... As far as vac leaks, I'm not understanding what else you are referring to.
You may have vacuum leaks through a crack in the intake boot and also between the carb insulator and the cylinder head. You can check for a vacuum leak by spraying a combustible such as carb cleaner or unlit propane in the area. If the engine revs change you have found a vacuum leak.

There looks to be a small nipple on each carb - are those for hooking up sync pressure gauges? Should those have a cap on them when not syncing?
Those are bowl vents. they should not be capped. If you look at the carb insulator you will see a screw head. That screw is removed and replaced with an adapter to source the vacuum for syncing the carbs.


Bob, I read a little about the rae-san system and how it deletes some of the coils. That sounds like a good idea. Can you provide a little more background on the charging stator though? Is there a brand new option? I am still running with a junk-yard stator right now and it isn't aftermarket. Some part #'s of the equipment I should get would be helpful
Your bike has CDI ignition and would normally use a G47 stator which includes coils used to generate the current to fire the spark plugs. If it is still charging your battery it does not need to be replaced (assuming that your source coils or pickups have failed and you install a Rae-San system). If you are removing the rear cover for other work you can replace the G47 stator with a G8 stator, as fitted to the GL500. Both stators are readily available new aftermarket.
 
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As you know, the alternator's stator is mounted inside the back of the engine where the engine's flywheel (which has permanent magnets mounted in the edge) acts as the alternator's rotor. The Capacitor Discharge Ignition is powered & triggered by special windings on the stator so there is only room on the stator for charging system windings that are rated at 150W, even though the stator has the same footprint as the ones in the later models that have Transistor amplifier Ignition, which is powered by the charging system, allowing the full stator to be used for charging windings, resulting in an alternator rating of 252W.

The CDI is commonly referred to as a "G47" type while the TI type is called a "G8" (see pic below). You can run a Rae-San or Ignitech ignition with the original 150W stator but between that and the headlight and there isn't a lot left over for keeping the battery charged if you want to run any electrical accessories. Many people who change to modern ignition systems also change to G8 stators for that reason but if the original one is keeping our battery charged you could wait until you have to take the engine apart for something else (like the camchain) and replace it then.

There are a number of reputable sources for aftermarket stators and I'm sure people who have bought them will let us know which ones are good.



BTW, There is a 3rd stator option: The footprint of the stator is also the same as the stator used in the GL1000,1100 and possibly 1200. The 1000/1100 stator is rated at 300W so I installed the one from my 1000 parts engine in the GL500 when I had it because it was my winter vehicle and I often needed to run handlebar heaters and the sidecar headlight as well as all of the other lighting &c and the stereo at the same time on days when starting was harder so the battery needed more to re-charge it. When I for the 650 I bought a used stator from a late model 1100 for it, figuring it would be one of the newer used ones. When it died 7 years later I re-wound it myself (just because I wanted to try doing one). When the engine it was in died I replaced it with one from a GL500 and since there was no other reason to open it and I had retired (= I get to choose when I go out in the winter) I've been managing fine with the 252W stator.
 
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