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Discussion Starter · #1 ·
I have been fighting miss/backfire/popping issues too long
. I even bought a parts bike to help me sort this one out. The parts bike ran pretty good, but has different mufflers on it so I figures that was what was causing it not to have quite as much power as it should. (Oh, It's an 80 by the way.) I have swapped coils, got rid of the resistors, aluminum rod in the plug boots and last thing I did was swapped the carbs and tank form the parts bike. I swapped the tank because the 81 has the vacuum petcock and the 80 carbs don't have a place to pull the vacuum. Anyway, it felt strong, no popping etc up to 4000 RPMs. As soon as I hit 4000 it started missing. Upshift to the next gear, and it runs fine till 4000 rpms and it acts up again. I stopped at a stop light and it seemed to get worse, and the more I rode it, the worse it seemed to get. I rode it home full throttle, popping and backfiring the whole way, and barely enough power to pull. I'm gonna rebuild my original carbs and put them back on. Anything else I should be looking at? Thanx guys. This is really starting to get to me. I wanna go from this
to this
!!!!!!
 

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Sounds to me like it could be your stator/CDI if swapping carbs doesn't make a difference, but the parts bike ran ok with the same carbs. Try swapping the CDIs and see what happens.
 

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I'm with Cramer.



My stator failed recently, but it was a different failure than the one you may be experiencing. With what I've now read on the subject there appears to be 3 separate coil functions of a stator; 1) low speed coils, 2) high speed coils, 3) charging coils. Seems like you're having a problem with either (or both) the low and high speed coils. In my case the charging coils failed and when my battery ran out of juice, the bike just stopped. Fortunately that happened when I was stopped at a light.



Check this web site out (below). There are resistance and voltage checks you can easily make at the stator connector. I did the tests, and sadly my stator failed...which I kind of knew was going to happen, but it at least confirmed my suspicions. Now I'm in a complete triple bypass procedure and the motor is out. Good luck.



David's web site
 

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See what you get for readings:





 

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Johnny, - your bike won't have the ignition coils on the stator as your 650 is a TAI bike.



You stator is the G8 that only has the charging [battery] coils.
 

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Ok lets dial this back.



The original problem before changing parts was backfiring/popping but did the bike have the power limit that you have now?



Have you checked the Stator as above?



What resistance readings are you getting from two plug connector at the main ignition connector block?



Set meter to 2000 ohms and test the harness blue wire to the frame and then the white to the frame at the small two block connector near the CDI unit.



Mine read White 360 ohms

Blue 450 ohms.
 

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Do you know the history of this bike?

Was this something it just randomly started doing and was fine for some period of time before?

or is the bike new to you and this has been an ongoing issue?



I ask because if it is has an unknown history I would go through and check the Valves very closely. As I experienced recently press (pretty hard) on the rocker arm over the push rods before setting the gap.



I would normally say carbs but it the problem stays with the engine/frame and not the carbs/coils.
 

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Discussion Starter · #8 ·
Do you know the history of this bike?

Was this something it just randomly started doing and was fine for some period of time before?

or is the bike new to you and this has been an ongoing issue?



I ask because if it is has an unknown history I would go through and check the Valves very closely. As I experienced recently press (pretty hard) on the rocker arm over the push rods before setting the gap.



I would normally say carbs but it the problem stays with the engine/frame and not the carbs/coils.
It ran fine late fall/early spring. It seemed to start when I washed it. I did the plug boot mod, swapped coils and now carbs. I adjusted the valves back last summer and it was fine after that.
 

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It ran fine late fall/early spring. It seemed to start when I washed it. I did the plug boot mod, swapped coils and now carbs. I adjusted the valves back last summer and it was fine after that.


Then I am with everybody else.

Test the CDI modules (swap off the parts bike if you want but it is also questionable until proven good) and test the stator.

Let us know what you find.
 

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This may be a long shot, but the manual says to "service the crankcase breather more when ridden in rain, dropped, or washed frequently." Check your air filter, and crankcase breather. I doubt that it'd be causing those kinds of problems, but hey...it doesn't hurt to check.



I still have my money on that CDI or stator though. Get yourself an ignitech, it'll save yourself a world of trouble, and make your bike seem like it's brand new again. But my mentality is that if your parts bike ran fine but your current bike doesn't, and swapping the carbs makes no difference, then swapping CDIs will almost certainly tell us *something.*
 

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Discussion Starter · #11 ·
This may be a long shot, but the manual says to "service the crankcase breather more when ridden in rain, dropped, or washed frequently." Check your air filter, and crankcase breather. I doubt that it'd be causing those kinds of problems, but hey...it doesn't hurt to check.



I still have my money on that CDI or stator though. Get yourself an ignitech, it'll save yourself a world of trouble, and make your bike seem like it's brand new again. But my mentality is that if your parts bike ran fine but your current bike doesn't, and swapping the carbs makes no difference, then swapping CDIs will almost certainly tell us *something.*
Swapped CDI, and coils both from the parts bike yesterday, and it is ALMOST perfect as far as running. Choke works, idles good, and just a slight miss around 6000 rpms, but goes away at about 6500. I am going to put the original carbs/tank back on and I think I will be back to 100% finally and I can RIDE!!!!!!
 

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Glad it worked out!
 

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Johnny, - your bike won't have the ignition coils on the stator as your 650 is a TAI bike.



You stator is the G8 that only has the charging [battery] coils.




CXPhreak....thanks...I'm still learning too. Where do you get replacement stator's for these bikes?
 
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