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1982 CX500C
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Discussion Starter · #1 ·
Hello,

I'm working on a 1982 CX500 I picked up a couple months ago. It was running when I got it but then didn't run after a month of not working on it. While diagnosing the issue, I've been turning the engine with no problems. It started with starting fluid and then sputtered and died since it was getting no fuel. I cleaned/rebuilt the carbs and went to start the bike and that's when this new issue began.

The bike wants to start. It turns over, then you hear a little poof of the exhaust, then the starter spins without turning the engine. When I release the start button, there is a little rattle. I've linked a video below of what it sounds like.


Any ideas of what could cause this? I'm thinking it may be the starter or starter clutch but I'm not familiar enough with the mechanics to know for sure.

Any advice is appreciated. Thanks!
 

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1978 CX500 "The Grub", 1983 GL650I "Nimbus"
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For the instant that it fires, the flywheel turns faster than the starter and the starter clutch disengages. Could be weak springs in the starter clutch or a weak battery. An easy test would be to charge it overnight and see if it's any better tomorrow.
 

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Discussion Starter · #4 ·
I charged the battery overnight. That seems to have solved the issue where the starter clutch was disengaging, however the bike is still not starting. It turns over and fires momentarily as it did before, but then goes back to to turning over with the starter.

I will give the fuel system another once-over tonight. Anyone have suggestions of what to look for specifically? I have rebuilt the carbs and petcock. Gas in the tank. New plugs. Good compression. Maybe it's just flooded from my previous starting attempts?
 

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Have you downloaded a copy of the factory service manual for your bike from the wiki, link in my signature? If you have, turn to the troubleshooting section and follow the suggestions for a no start condition.
 

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1982 CX500C
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Discussion Starter · #6 ·
Thanks for the resource! I have the Haynes manual, nothing quite as useful as that troubleshooting chart though. I'll work through this over the next couple days to see if I can pin the issue down.
 

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Discussion Starter · #8 ·
I cleaned the carbs as thoroughly as I could without having an ultrasonic cleaner. Verified the jets were clear. Float levels are good, which is the original problem I went to fix when taking the carbs off, the right cylinder was not getting fuel. The engine wouldn't fire at all before the rebuild. I do not have Larry's Carb book.

Still possible I fouled something up. Learning every day.
 

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I cleaned the carbs as thoroughly as I could without having an ultrasonic cleaner.
It might take several attempts the first time. Did you extract the idle circuit emulsion tube from under the rubber plug?
 

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I was wondering the same thing about the totality of the cleaning job. Not that it wasn't a diligent job but i hear over and over again on this site (and Larrys book) that everything has to come apart, ultrasonic cleaning and wires/drills put through the small passages.
 

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'84 CX650E that is evolving into a GL500
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Did you pre-fill the carbs before attempting to start it? If not the problem could be as simple as not enough fuel in the float bowls for starting.
Your '82 CX's vacuum petcock has 2 valves, a manually controlled valve that works the same as a non-vacuum petcock, allowing you to select between ON, OFF and REServe and a vacuum valve that prevents fuel from entering the manual valve when the engine is not running. The problem is that even with the manual valve set to ON the vacuum valve won't let any fuel into the carbs unless the engine is turning fast enough to produce vacuum to open it so you have to crank the starter long enough for the engine to supply enough vacuum to the petcock to open the valve for a long enough time for the float bowls to re-fill and it is pretty easy to run the battery down doing that.

But there are other ways to fill the bowls:
1) Disconnect the fuel line from the petcock, connect a funnel and pour 90cc of fuel in directly. (This the method I recommend).
2) Disconnect the vacuum line from the petcock (this is the small barb farthest from the petcock's main body), connect a short piece of clean tubing in its place and apply vacuum (with a vacuum pump or just suck with your mouth) for about 10-15 seconds.
3) Disconnect the drain/vent line from the petcock (this is the small barb between the vacuum line and the main body), connect a short piece of clean tubing in its place and blow gently into it for 15-20 seconds.
4) If you spray enough starting fluid into the air filter and start the engine on that it might run long enough to fill the bowls but it could take several attempts.

You can check if there is fuel in these carbs by connecting a piece of clear tubing to the overflow/drain hose barb on the bottom of the float bowl and holding the open end higher than the float bowl while opening the drain screw half a turn (the level should be just below where the float bowl meets the carb body).

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).
 

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Discussion Starter · #13 ·
Did you extract the idle circuit emulsion tube from under the rubber plug?
I did not. I was not sure how to remove it as it's not slotted for a screwdriver. I read somewhere that some are, some are not.

everything has to come apart, ultrasonic cleaning and wires/drills put through the small passages.
I could go through the carbs again and try to be even more thorough. I did run brass wire through all the passages.

Did you pre-fill the carbs before attempting to start it?
Carbs pre-filled by sucking on the not so clean vacuum line. I did not check the level using the clear tube on the drain though, that's a good tip. Also, thanks for the welcome. This site has been a great resource already and I image I'll be through regularly as I work get this bike road worthy.
 

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I did not. I was not sure how to remove it as it's not slotted for a screwdriver. I read somewhere that some are, some are not.
I use an EZ-Out, but it's easier and safer to tap the top of the tube for a certain size screw to draw it out. Anyone have the link handy?
 

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I use an EZ-Out, but it's easier and safer to tap the top of the tube for a certain size screw to draw it out. Anyone have the link handy?
I think your mileage will vary with tapping vs. easy out. I had some spare carbs and tried both methods. My results were the ez-out was my choice of the two. It is nerve racking seeing the ez-out twist hoping it won't break. I also found if i put the body in the heated ultrasonic before trying the ez-out it seemed the heated body helped the removal. Hot water would have the same effect if you don't have an US cleaner.

BTW, as Larry's book recommends - use a name brand ez-out like MAC, Snap-On ect.
 

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Discussion Starter · #17 ·
Thanks for all the input everyone. Good news, it runs! (but poorly)

The fuel/air mixture is obviously off. Engine rev's high with closed choke on startup, runs for a bit with open choke then can't get enough fuel and dies. Easy enough to work with.

The right cylinder exhaust is much cooler than the left, also has occasional popping. Possibly a plug or timing issue? Maybe worse as there is an occasional knock in the engine. The engine will eventually be getting a top-end rebuild at a minimum, possibly more depending on condition. I will however be moving on to other parts of the project for now.

Also thanks for the tips on the EZ-Out. I will try it out next time I have the carbs apart.
 

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Discussion Starter · #20 ·
I'd work on carbs first. unless you have a KNOWN top end issue leave it alone for now. get Larry's book
Have you performed a compression check to confirm the motor needs a top end rebuild?

Have you checked the FSM to see how involved a job a top end rebuild is on these motors?
I know carbs need work. Compression is good and I do understand what a top end rebuild involves. This is a resto-mod project that I am using to learn the mechanics so the engine rebuild is by choice. I just wanted to get the bike running so I knew it was possible before stripping the bike down.
 
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