coils going bad?

P

primo

Been Around the Block
here are my symptoms on my cb350.

runs fine until the bike warms up then runs rich. also, backfires for just a sec and goes away and runs rich again.

valves adjusted, new points, condensor, charged battery, timed with gun, new plug cap but stock coil.

can someone link me on how to test the coil or post here how to check it?

thanks

JP
 
i've just opened up the points cover and fired up the bike. the bike idles well but i only see a visible arcing in the right points but not on the left. so i checked unscrewed the left spark plug and started the bike and there was spark. but i'm still concerned about the lack of spark on the left points. does this have to do with the bike running poorly as mentioned above? is my hunch correct and the coils are failing? i don't mind replacing them but i would like your thoughts and expertise.

its not water in the tank
 
No sparking across the points is a good thing.
It means the condensor is doing its job.

Sounds more like a fuel or carb issue.

Cheers.
 
I read somewhere online before that bad coils will run for about half an hour, overheat, and stall out. After cooling down, the coils come back to life like nothing happened.

Also, a bad coil will begin to fail at higher rpm (naturally) but still appear fine at lower rpm's.
 
dynatec coils are a good investment. even if they end up not being the culprit, its good assurance for the future.


did you sand down the points?
 
Rocan said:
dynatec coils are a good investment. even if they end up not being the culprit, its good assurance for the future.


did you sand down the points?
Click to expand...

yes i did
 
Why did you sand new points??? define running rich,,,black smoke?? rough running?? is it one cylinder or both at the same time.Is it a good battery,,or an old one thats been charged,,did the new caps thread into clean copper wire,,,,are the wires toast,are the connections sound ignition and electrical,,,is the ignition and or the kill switch corroded,,,,,sorry about the big basket of eggs,,,,but it's easter ;D......good luck
 
Wee Todd said:
Why did you sand new points??? define running rich,,,black smoke?? rough running?? is it one cylinder or both at the same time.Is it a good battery,,or an old one thats been charged,,did the new caps thread into clean copper wire,,,,are the wires toast,are the connections sound ignition and electrical,,,is the ignition and or the kill switch corroded,,,,,sorry about the big basket of eggs,,,,but it's easter ;D......good luck
Click to expand...

i didn't sand the new points; just made sure there was no grease or grim on it. bike running rich as in throttling and mid range spluttering until main jet kicks in to clear it. not sure about one cylinder. not sure about the battery but PO claims it as a newer one; its charged up and seems fine. new caps into cleaner wire. not sure how to check the ignition and electrical with ohmeter yet. running bike with no kill switch but that shouldn't be the source of the problem.

but i wanna know if about the arcing on the points. much more arcing on the points when bike is idling on the right than the left (left almost no activity) but there's spark on both plugs and i can feel the backpressure from both muffler. should i be worried about the points?

its either a carb issue, coil issue or an old corroded wiring harness but i doubt the last one.

any more solid leads?
 
I had a problem with my kill switch so I bypassed it by connecting the black coil wires to the power wire for the horn and signal relay with another wire that I made with 2 extra female pin connectors. Worked very well, ignition seems to be a bit stronger. I'm thinking it's maybe due to he shorter wire length therefore less resistance for the power to travel. Also the early 350s didn't have kill switches so they aren't really necessary, just convenient.
 
DrJ said:
I had a problem with my kill switch so I bypassed it by connecting the black coil wires to the power wire for the horn and signal relay with another wire that I made with 2 extra female pin connectors. Worked very well, ignition seems to be a bit stronger. I'm thinking it's maybe due to he shorter wire length therefore less resistance for the power to travel. Also the early 350s didn't have kill switches so they aren't really necessary, just convenient.
Click to expand...

one member on hear sufficiently scared me about not having a kill switch.

he had his bike on top of him, throttle gunned, tire rubbing on his body. no kill switch. you never know when you need it.
 
As far as testing them, its as simple as checking to see if they put out spark throughout the RPM range and dont shut down or overheat.
 
primo said:
here are my symptoms on my cb350.

runs fine until the bike warms up then runs rich. also, backfires for just a sec and goes away and runs rich again.

valves adjusted, new points, condensor, charged battery, timed with gun, new plug cap but stock coil.

can someone link me on how to test the coil or post here how to check it?

thanks

JP
Click to expand...

Couldn't be a mixture issue? Sounds like your ignition is in good shape, if none of theses solved your issues I would double check the carbs. Could be that one of your floats is set wrong or stuck, fouling the plug on one side. Also as your temperature rises, the fuel atomizes better and the mixture gets richer.
 
im havein the same problem with a buddys 350 running super ritch with new tood henning racing jeted 30mm carbs im goint to install new points and swap for a known good coils and go from there maybe get some new spark plug caps also check voltage at the coils
 
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