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Discussion Starter #1
I've got a '79 CX500C, and it was running great until just recently.

On a completely cold start, I can start it on 1/2 choke and it will run for about 30 seconds, at which point (choke or not), it will begin to roughen up and eventually die.
After dying, it's difficult/impossible to get running again. If I can get it started, it's with WOT, and I have to keep on the throttle to keep it running.

The following modifications have been done to the bike:
- K&N pod filters
- Jet kit (110/127 and shimmed needle) from 6Sigma
- Slip-on pipes (slip-on mufflers with the baffles removed).

After these modifications, the bike ran for several months with absolutely no issue.
The issue started on a Friday when I was coming home after filling up. When I pulled into my driveway and squeezed the clutch, the bike immediately died, and wouldn't start again until I let it sit for a bit.
The next day it was difficult to start, and would bogg down and backfire up to about 3500rpms, where it would smooth out. After a while of riding, this went away.
I parked the bike, and when I came back it was again difficult to start and did the same bogging/backfiring. The bogging went away after a while and I took it for a 2hr ride with no issue. I took it home and left it overnight.
In the morning, I had difficulty starting it yet again, and it still would not run right.

I've done the following troubleshooting:
- Disassembled both carbs and ultrasonic cleaned the bodies and components.
- Cleaned out jets.
- Dumped out the gas and got fresh 93 from a different station.
- Changed both spark plugs.
- Checked spark.
- Checked boots on carbs for leaks.
- Pulled fuel filter to make sure it wasn't obstructing flow.
- Checked fuel was reliably coming from tank on both On and Res.
- Swore at bike.
- Angrily drank beer at bike.

Nothing has worked for me so far. I'm stumped.

Any help here would be GREATLY appreciated. I'm tired of not riding this thing.
 

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I would continue to employ the last two strategies with increased vigor!

PS. I would suggest another course of action but I don't know enough, I will leave that to the other guys with more knowledge.
 

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return to original jetting and try to run it .
I suspect you are overfueling badly
 

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It ran well up to the point of refueling, then began to fail. You have done
everything that would remedy a fuel problem, do a stator check and look
at your wiring and coils. May be electrical failure that just happened to begin with a fill-up.
 

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Discussion Starter #7
Oh whoa, just checked back to see all these responses. Thank you everyone, I'll give all your suggestions a look and reply back in a day or two.
 

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Discussion Starter #8
rscottp, I've been religiously repeating those methods every night for the last few nights.

So far the bike just sits there. I'll report back after continued efforts. :D
 

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Discussion Starter #9
Okay, so!

I returned the carbs to stock Jetting as per muzza's suggestion. This FINALLY got me somewhere.
I reset the jets to 78/112, and removed the spacers from the needle.

The bike will now start and idle normally, but bogs down as soon as I add any throttle.

Not sure where to go next. Will be pouring over all documentation I have for the remainder of the night. I see many beers in my future.

Oh, I also ordered Larry's carb book, which should be here soon.
 

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Discussion Starter #11
I have pods, but still have the stock H-box in place.

I had asked for a set of 90/120 from 6Sigma, but they sent me larger jets, and incredibly confusing and cobbled together instructions.

They also told me low-RPM stumbling would be due to float height. I'm gonna have a look at that today.
 

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Float height is not likely the source of your problem. Float height is not adjustable unless your carburetors have floats with the metal tang; most are plastic. Wait on the carb book before doing anything to the carbs. Run the stator checks mentioned in a previous post.
 
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How did your clean out the jets? I gave up on the press in jets. Went to 1983 carbs that screw in. Made the work so much better. Got them off of the 650 engines. Changed them to fit into my 500c. Just the way they mount. Spacing. Used the jets that came with them.
 

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Discussion Starter #15
My floats actually do have the metal tag. I also have all screw-in jets too. Never heard of the press-ins.

I believe the carb book is coming in tonight, and I'm gonna check the stator either tonight or tomorrow.
 

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Aftermarket float needles can be a crapshoot for length and will put your float levels out if you have non adjustable floats.

Worth checking, but not particularly likely to be far enough out to be your issue.
 

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Discussion Starter #18
Unless someone upgraded your carbs, you still have the press in jet deep inside the carb. without the book it would be easy to overlook.
Oh! You mean the slow jet. 6Sigma's kit included a drill bit, and my rebuild kit included what appears to be another jet. Should I drill it out and replace it?
 

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Please wait for Larry's book to show up before you try to remove the press in jet.
 
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