[drummertom]

OK quick history. Washed the bike and it started running rough. Ended up changing plug wires and went to iridium plugs. Still had popping and backfiring under acceleration. In the mean time, changed the oil and overtightened the drain plug, so I replaced the front cover and left out one of the sleeves and O rings, so I had no oil pressure. Got a new gasket, repl front cover again yesterday, spun the motor with no plugs and had oil pressure, so I put it all back together and went for a quick ride. It has no missing or popping, plenty of oil pressure, but is very under powered. It revs up smooth but just doesn't have the power it did. I have not touched the carbs (yet). Someone mentioned in another thread that when you have problems, it usually relates to something you just did, so that is why I mentioned all of the above. Any ideas from the experts? It felt good to finally ride again, but I really want to get this thing back to it's former glory!!!!! Thanx in advance for your help.

 

[Reg in Bristol]

Wild guess if its a CDI bike

the contacts under the kill switch button collect crap/crud whatever

which tends to be absorbent

One contact is connected directly to the CDI stators charging coils and gets

shorted to ground to stop the engine

IF there is moisture in there, it may be leaking some stator power

across the open contacts to ground.



If you open it up to check/clean it, be careful not to lose

the tiny circlip, ball bearing and spring as this is easily done



Its a guess that's all

 

[Blue Fox]

Do you have a good spark on both sides? It almost sounds like you are running on one cylinder. I had a similar issue one time after I had replaced the carbs. Turns out that when I swung the coils up and out of the way, I pulled the connector partially out of the coil connection. The bike ran, but was very doggy. I only went a mile or so before returning to trouble shoot. How did you change the plug wires on your CDI bike? Usually all the CDI coils have the wires molded into the windings and are non replaceable. I think you have a high tension voltage arcing or leaking to the frame somewhere. Running the bike in the dark may pinpoint any arcing and point to the bad area.

 

[drummertom]

Do you have a good spark on both sides? It almost sounds like you are running on one cylinder. I had a similar issue one time after I had replaced the carbs. Turns out that when I swung the coils up and out of the way, I pulled the connector partially out of the coil connection. The bike ran, but was very doggy. I only went a mile or so before returning to trouble shoot. How did you change the plug wires on your CDI bike? Usually all the CDI coils have the wires molded into the windings and are non replaceable. I think you have a high tension voltage arcing or leaking to the frame somewhere. Running the bike in the dark may pinpoint any arcing and point to the bad area.

Both cylinders are firing. Cranked the bike in the storage building with the doors closed and could not see any arcing. I guess I'll check the switch next.OBTW, I changed the plug boots, not the wires. Sorry for the error.

 

[Blue Fox]

Well, that eliminates a couple of suspected areas. I still think it is electrical, and the key is that you said it started after you washed the bike. How about the drain holes around the spark plugs? Are the holes open and the inside around the plug clean? Did the problem surface as soon as you washed it, or did you replace the plug caps and then it surfaced? It may be possible that the very end of the plug wire where it enters the plug cap is bad. If you have enough wire, cut a 1/4" or so off and try re-threading the cap on. Have you checked the resistance of your caps with them off the wire? I seem to remember that that are usually around 5-7k ohms when operable. Someone correct me if I am off on this number.



You said you couldn't see any arcing while cranking in the shed. If you can, try letting it run, maybe even with the tank off, in the dark to observe around the coil area too. I know you say that you have spark on both sides, but when under operating conditions, sometimes a weak spark will not fire the plug under compression.

 

[drummertom]

Well, that eliminates a couple of suspected areas. I still think it is electrical, and the key is that you said it started after you washed the bike. How about the drain holes around the spark plugs? Are the holes open and the inside around the plug clean? Did the problem surface as soon as you washed it, or did you replace the plug caps and then it surfaced? It may be possible that the very end of the plug wire where it enters the plug cap is bad. If you have enough wire, cut a 1/4" or so off and try re-threading the cap on. Have you checked the resistance of your caps with them off the wire? I seem to remember that that are usually around 5-7k ohms when operable. Someone correct me if I am off on this number.



You said you couldn't see any arcing while cranking in the shed. If you can, try letting it run, maybe even with the tank off, in the dark to observe around the coil area too. I know you say that you have spark on both sides, but when under operating conditions, sometimes a weak spark will not fire the plug under compression.

Fired it up in the shed with the gas tank off, headlight and parking lights off, still see no arcing. Can I pull the plugs and look at the spark at the plugs without hurting the CDI?

 

[drummertom]

Fired it up in the shed with the gas tank off, headlight and parking lights off, still see no arcing. Can I pull the plugs and look at the spark at the plugs without hurting the CDI?

OK I think I may finally may be making some headway on this. At least I hope so. I changed the coils today. The popping and backfiring came back, and the only constant is the plug boots themselves. One of them seemed a little corroded where it screws in the plug wire. I cleaned it the best I could, but maybe that wasn't good enough. It also has the resistors in them and I think I read somewhere that you can eliminate these and just use a piece of solid brass. Is that correct? Also, any suggestions on how to clean the part of the boot that screws into the plug wire?

 

[Shep]

Resistor removal/replacement,



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=8&t=84



Brass screw can be cleaned by sticking the boot upright using a bit of plasticine and dropping some lemon juice/white vinegar into it and leaving for half an hour.The acid will help etch it clean.Then spray with some switch cleaner or use some clear alcohol and dry out.



If you get fed up with the resistor type Spark plug caps you can buy the none resistor type ones that my UK CX500s use from here(Several US members get stuff from Wemoto:superb service)



http://www.wemoto.com/bikes/Honda/CX_500_A/79-80/



but then change plugs to,

NGK DR8 ES-L or NGK Iridium DR8EIX as they contain the resistors required as part of the CDI ignition circuit.The TAI(Transistor Advanced Ignition) engines don't seem to care about the resistors TTBOMK.

 

[drummertom]

Resistor removal/replacement,



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=8&t=84



Brass screw can be cleaned by sticking the boot upright using a bit of plasticine and dropping some lemon juice/white vinegar into it and leaving for half an hour.The acid will help etch it clean.Then spray with some switch cleaner or use some clear alcohol and dry out.



If you get fed up with the resistor type Spark plug caps you can buy the none resistor type ones that my UK CX500s use from here(Several US members get stuff from Wemoto:superb service)



http://www.wemoto.com/bikes/Honda/CX_500_A/79-80/

OK I've got iridium plugs and resistor in the plug boots. Could that be too much resistance?

but then change plugs to,

NGK DR8 ES-L or NGK Iridium DR8EIX as they contain the resistors required as part of the CDI ignition circuit.The TAI(Transistor Advanced Ignition) engines don't seem to care about the resistors TTBOMK.

OK I have iridium plugs and the resistors in the plug boots. Am I creating too much resistance?

 

[Shep]

I ran one of my bikes with resistor caps and plugs and it didn't seem to mind.It's not recommend the other way round e.g NO resistor in the circuit.

 

[drummertom]

OK For us guys on this side of the pond, just what is plasticine?

 

[Shep]

OK For us guys on this side of the pond, just what is plasticine?

Kids moulding stuff,



http://cgi.ebay.com/Craft-Art-Model...37?pt=AU_Kids_Arts_Crafts&hash=item1c1bbd8d75



Anything really that will temporary hold the plug cap up even double sided tape

You could clamp it lightly in an adjustable wrench.

 

[thackney]

Check the resistance through the caps, they are probably corroded internally and will have very high or infinite resistance. I have a couple out in the garage that I rebuilt with brass rods if you are interested. I could use your old ones to rebuild for someone else.

 

[drummertom]

Check the resistance through the caps, they are probably corroded internally and will have very high or infinite resistance. I have a couple out in the garage that I rebuilt with brass rods if you are interested. I could use your old ones to rebuild for someone else.

What u want for um exchange?

 

[Shep]

I even have a none resistor plug cap here that has,"Infinite" resistance

Shagged inside/breakdown and it only has the two components

 

[thackney]

I will PM you re: plug caps.

 

[drummertom]

Resistor removal/replacement,



http://globalcxglvtwins.hostingdelivered.com/viewtopic.php?f=8&t=84



Brass screw can be cleaned by sticking the boot upright using a bit of plasticine and dropping some lemon juice/white vinegar into it and leaving for half an hour.The acid will help etch it clean.Then spray with some switch cleaner or use some clear alcohol and dry out.



If you get fed up with the resistor type Spark plug caps you can buy the none resistor type ones that my UK CX500s use from here(Several US members get stuff from Wemoto:superb service)



http://www.wemoto.com/bikes/Honda/CX_500_A/79-80/



but then change plugs to,

NGK DR8 ES-L or NGK Iridium DR8EIX as they contain the resistors required as part of the CDI ignition circuit.The TAI(Transistor Advanced Ignition) engines don't seem to care about the resistors TTBOMK.

OK I took the boots apart yesterday and soaked them a little (about 30 minutes) like you said, and I let the screws soak too. Put it all back together and on my test ride it did seem to be better. Under about half throttle it does fine, but under full throttle, I am still getting some backfire and popping. I'm gonna replace the resistors with brass rods today and see if that fixes it. I'll of course post what happens. THX!!!!!

 

[Shep]

Backfires and popping can be exhaust leaks,carb leaks/ problems(Air Cut-off Valves) wrong float heights.