Topic: 74 cb550, electrical issue suspect bad coil.

[stolle]

Awhile back I was cruising down the highway and the bike started to feel like it was running out of gas so I switched to reserve and no change limped it home. It was running on two cylinders 1 and 4, 2 and 3 were not firing. I found that the 2/3 points were arcing like crazy, replaced the condenser and the arcing stop and the bike ran normally again. Last night I go to start it and the neutral and oil lights dim like the battery is dead bike won't start (kick only it has no starter motor) ran before this but started sputtering like it was before when the condenser went bad, not near as bad though. I call a friend to pick me and the bike up by the time he gets there the bike starts. We still load it in the truck. When I get the bike home I immediately check the condenser, it seems fine. There is a random high amp draw. Sometimes it's there some times its not, I traced it to the 2/3 coil this is the one that had the bad condenser. I checked the coil per the write up on here and it checks out. When it's hooked up is when I have the issue. Is it possible the coil could have a short to ground that's only there when power is applied. I suppose the bad coil could have been the reason my condenser went bad? Anyway any insight is appreciated.


Thanks

[calj737]

You say nothing about the status of your battery. If you measure the 2 different coils, are they the same? If you unplug both cols from the harness, and measure the coils resistance, is it the same as it was plugged into the harness? Are there other non-stock electrical components? A new, higher wattage headlight? Points good? Plug wires and caps?

Need more data...

[stolle]

I made the entire harness, I will tell you that it matches the stock harness as far as the ignition goes there is nothing as far accessories just a headlight and a taillight. With the ignition on the only thing that has power is the led taillight and the stock idiot neutral and oil lights. It has ran perfectly fine now for 700 miles. The battery is brand new, I thought that was the problem. I bought one this morning still does the same thing. Plugs and caps are new points and condensers had about 700 miles points gap is fine set at 14 thousandths. Both coils measure the same across primary and secondary there are no shorts to ground I have rang out every circuit on the bike, there aren't many. Everything is clean. I'll do some more testing on the coils and report back.

[calj737]

Thats good info, but entirely vague. If you want assistance diagnosing electrical, best to work with numerical data, not "everything tested good".

[stolle]

I should just asked if coils short to ground and if a bad coil would kill a condenser. I don't remember ever reading anything about testing coils to ground.

[540nova]

Your coil absolutely can short to ground. Here is something to read...


1974 CB450, 2006 CBR1000RR