CX500C 1979 over revving at idle
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Joined
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6,296 Posts
Check your throttle cable routing.
That’s a good point. The routing is ok. The cable needs to be lubed also but it has push/pull cables and I can see the throttle snap back ok on the carb. Blipping is ok until mid revs and then races away.
It sounds like the vacuum piston is floating. Have you made any non-stock mods that might affect the carbs? Pod filters, maybe?
Joined
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25 Posts
check acv and intake boots for leaks.
Yep. Intake boots. Have bought replacement boots/manifolds. Thanks!
Update. Manifold/boots replaced. Racing gone but still not idling correctly and overflowing rhs carb. I stated in the original post that the carbs had recently been rebuilt and by that I meant that they had been done several years ago and they had been drained and not used. I took them apart and the rhs had not been rebuilt and had crusty jets, crud in bowl and the floats had wear from hitting the bottom of the bowl. The lhs carb was pristine. Root cause analysis indicates that too much beer was consumed during that rebuild. Can anyone recommend a good rebuild kit for the carb?
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24,271 Posts
What is different about the oem and aftermarket jet I wonder?
Generally manufacturing precision. Regarding float valves it's the precision and the materials. The aftermarket are made from [email protected]
Generally manufacturing precision. Regarding float valves it's the precision and the materials. The aftermarket are made from [email protected]
The better carb kits don't include the metal parts because the people who put them together understand that 1) they are rarely worn or otherwise deteriorated enough to need replacement and 2) they can't get parts that approach the quality of the originals for less than they cost at your local Honda dealer.
This pic of an aftermarket float needle shows how bad some of the aftermarket stuff can become in a short while (not to mention the parts that are out of spec to begin with). Yes, that is the chrome peeling.
Photo from Randakk's blog, provided by Mike Nixon. I recommend reading the page it came from
www.randakksblog.com
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 present problem aside 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).
This pic of an aftermarket float needle shows how bad some of the aftermarket stuff can become in a short while (not to mention the parts that are out of spec to begin with). Yes, that is the chrome peeling.
Photo from Randakk's blog, provided by Mike Nixon. I recommend reading the page it came from
More Problems with Aftermarket Float Valves | Randakk's Blog
The factory float valves often last longer than the motorcycle. They're also expensive. But, I will not use aftermarket float valves, and here is why
www.randakksblog.com
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 present problem aside 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).
Thank you for your warm welcome, Sidecar Bob. I have added those details to my profile. Thanks also for the advice on rubber components, especially the brake lines, which I shall now seek to replace. A little background - my friend gave me a CX500 back in 95 when I moved over to the states from the UK. We were less than wealthy students and the bike was my only transport. Loved it because it was the first big big I owned, my UK bike being an AR125. I went back home for a while and then came back to MO. My friend gave me another CX. Had it mothballed for over a decade. Really looking forward to riding again, with those nostalgic sounds and smells, hopefully not the nostalgic breakdowns.The better carb kits don't include the metal parts because the people who put them together understand that 1) they are rarely worn or otherwise deteriorated enough to need replacement and 2) they can't get parts that approach the quality of the originals for less than they cost at your local Honda dealer.
This pic of an aftermarket float needle shows how bad some of the aftermarket stuff can become in a short while (not to mention the parts that are out of spec to begin with). Yes, that is the chrome peeling.
Photo from Randakk's blog, provided by Mike Nixon. I recommend reading the page it came from
More Problems with Aftermarket Float Valves | Randakk's Blog
The factory float valves often last longer than the motorcycle. They're also expensive. But, I will not use aftermarket float valves, and here is why
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 present problem aside 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).
Joined
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8,206 Posts
hopefully not the "mice" smell
As I said, I was not overly wealthy, so freshly roasted mouse was a rare treat.
Thanks. Just looking this oil thing up and it seems like it could be one of several things. One other observation- I don’t think it was smoking from burning oil when I fired up last time.
Edit: solved. It was so embarrassingly stupid. I had used the external fuel tank to mix 2 stroke for the chainsaw. Forgot and hooked it up to the cx. There was some unmixed at bottom of tank. This would also explain it running like crap. Feeling like twelve types of duck head at the moment. Autocorrect.
I'm happy when it turns out to be something simple I've overlooked. It's a lot easier to fix than a real problem.
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