[Phil keen]

Hi all , dodgy cx running real bad after 5k revs , reading a lot on here about resistors in leads and caps , forgive my ignorance but I’m new to classic bikes (apart from my rd350lc)
The guy who sold me the bike when I quizzed him said he replaced the coils, ht leads and plugs to Honda’s spec so do u all think I can rule out conflicting resistors making the bike jerk over 5k revs ?
thanks

 

[Gerard]

Hi Phil , depending on the year of your bike two common problems are showing up. Cdi ignitions failures and second dirty carbs ( as in the mainjet getting restricted , get Larrys famous carb book). Myself clean carbs first , ( cheapest) and replace resisters with a piece of brass rod.

 

[reclinedrelic]

If it is a CDI bike the easiest first step is to do the resistance measurements. How to check or test the stator and pickups on a CDI Honda CX500 | MotoFaction Symptoms are similar to high speed source coil failure.

 

[bahn88]

You can easily check the plug caps with a multimeter...they just unscrew.. give em a good shot of contact cleaner and dry before refit....

 

[joethebike]

Had exactly the same symptoms on my TAI bike and the cure was new spark plugs, new ignition leads and lots of scraping and cleaning to clear the electrical path from the plug cap lead connector screw, through the spring and resistor to the spark plug connection screw.

 

[Sidecar Bob]

These links may help:

How to tell whether you have CDI or TI? Honda CX500, GL500, CX650, GL650: A closer look at the ignition components

Want to know whether your Honda CX or GL has a CDI or TI system, or looking for more information about each setup? Find out here!

motofaction.org

Note that all CX500 models/years except the CX500E (Sport or Eurosport) and the 1982 model CX500C (Custom) came with Capacitor Discharge Ignition (CDI) and the models mentioned plus the GL500 and all CX/GL650 came with Transistor amplifier Ignition (TI or sometimes TAI). But 40 years is a long time and more than a few of these bikes have had the engine replaced with one from a different model or year and we've seen a few early CX500s with TI engines.

Resistor Plugs, Wires, and Related Issues www.motorcycleproject.com

(Some models came with resistors in both the spark plugs and the spark plug caps and that didn't cause any "conflicts" but you really don't want resistor wires on any bike)

 

[Sidecar Bob]

You have now started 3 threads about the same problem. Multiple threads about the same problem (even if attacked from different angles) are frowned upon because it gets confusing when people answer in one thread without reading the others or without realizing that they are all related.
I considered merging them but I think in this case that would only make it even more confusing so I am posting links to the other threads in each of them instead.

I strongly recommend reading all 3 threads before replying in any of them.

Cx500 b 1981 misfires around 5000 revs

Hi all just got a beautiful cx and it misfires around 5-6k I have bought a 2nd hand cod unit that was confirmed working because it had an ignitech on it and I didn’t know if it was mapped to the bike so put an old fashioned cod back on but still jerking at same revs but better and smoother...

www.cx500forum.com

Right cylinder running hot

hi Hi guys , these plugs are 24 hours old and done 10 miles , the right one is very sooty Both new ngk dr8es , right cylinder heats up quicker than left , new Honda recommended coils been fitted, new ht lead , cdi is working BUT bike misfires / jerks over 5.5k revs and I thought it electrical...

www.cx500forum.com

 

[Randall-in-Mpls]

Note that all CX500 models/years except the CX500E (Sport or Eurosport) and the 1982 model CX500C (Custom) came with Capacitor Discharge Ignition (CDI) and the models mentioned plus the GL500 and all CX/GL650 came with Transistor amplifier Ignition (TI or sometimes TAI). But 40 years is a long time and more than a few of these bikes have had the engine replaced with one from a different model or year and we've seen a few early CX500s with TI engines.

Outside North America, didn't the later CX500 Standard switch the TI at some point Probably around 1982)?
Based on the engine serial number in one of the other threads, this appears to be a '78 or '79, therefore CDI.

 

[eric Livy]

Hi all , dodgy cx running real bad after 5k revs , reading a lot on here about resistors in leads and caps , forgive my ignorance but I’m new to classic bikes (apart from my rd350lc)
The guy who sold me the bike when I quizzed him said he replaced the coils, ht leads and plugs to Honda’s spec so do u all think I can rule out conflicting resistors making the bike jerk over 5k revs ?
thanks

Hi Eric in Scotland here.i had the same problem on . my cx it was the pickup,s were done that's why I'm swopping ignition from gLto cx does your cx start on one cylinder for 30sec,s when cold, that was another sign.

 

[Phil keen]

Hi Eric in Scotland here.i had the same problem on . my cx it was the pickup,s were done that's why I'm swopping ignition from gLto cx does your cx start on one cylinder for 30sec,s when cold, that was another sign.

Hi Eric , problem fixed now , it was the Honda approved coils that were playing up , replaced them with orange ones from eBay and she runs fine now 👍

 

[eric Livy]

Hi Eric , problem fixed now , it was the Honda approved coils that were playing up , replaced them with orange ones from eBay and she runs fine now 👍

Thanks, I did the same thing, was running OK but left carb was leaking, found it was the float valve tried changing it no joy, didn't matter what I did it leaked it was a OK before I stripped it, tried cleaning up the valve seat with a drill made it worse, now I need a new carb, managed to get a set on ebay but can't get bike to rev. Cleaned them, new jets floats and needles still won't run. Tick, s over will only rev on choke to 3.000

 

[nolimitz]

Go back to your old needles and brass from the "new" or old carbs. Most aftermarket needles are suspect junk