Coil a #1 and #4 keeps going bad

[Chicagoxs]

Just the one that went out. Then it went out again.

[dbeardslee]

So you were running it with one Magna coil, and one oem coil, correct?

[Chicagoxs]

Yes I had one coil from a magna and one original. I only could find one locally and wanted to get the bike running. It's the same coil pretty much just different shape.

[MPittma100]

Coil

Yes I had one coil from a magna and one original. I only could find one locally and wanted to get the bike running. It's the same coil pretty much just different shape.

Sounds like the coil simply failed.

[Chicagoxs]

Well yes I know the coil failed. I just think it's a bit fishy that the same side failed twice in two rides. And the other side is not affected and works perfect

[dbeardslee]

From what I can glean, Magna coils are about 2.5 ohms and the stockers are 3. Dunno if it makes any difference mixing different ohm ratings, but I sorta doubt it being such a small difference. Using one old high tension wire and one new one doesn't sound like a good idea, though.

Might not be a bad idea to put a DMM on your TCI and check the voltages, but I tend to agree with MP100 - sounds like a bad coil. Pretty coincidental, but that's the chance you take with used parts. That's part of the reason why I like Dynas - brand new coils with brand new wires. They cost a few bucks but sometimes you get what you pay for.

[Chicagoxs]

Yeah I knew that there could be a possibility of the used coil going bad. Like I said I just wanted to get it running. Can I test the voltage of the TCI without the bike running? I do not want to run the bike on two cylinders.

[dbeardslee]

Yeah I knew that there could be a possibility of the used coil going bad. Like I said I just wanted to get it running. Can I test the voltage of the TCI without the bike running? I do not want to run the bike on two cylinders.

You do the test with the ignition on, but not running. With the connectors in place and the ignition on check grey to ground (12v), white/red to ground (12v), black/white to ground (6v), orange to ground (12v) and red/white to ground (12v). You stick one probe in from the back of the connector to make contact at the connector, and just touch the other probe to the frame in a spot where you can get a good ground. It's also a good idea to get a reading on the battery, just so you know how much voltage you've got to start with.

I doubt it's causing your troubles, but while you've got the dmm out you might as well check the resistances to the pickup coils too. With the ignition off, pull the four wire connector off the TCI, and connect a DMM to the contacts inside the connector. They're in pairs - two wires go to one pickup and the other two go to the other pickup. Check wht/r to wht/gr and yel/gr to yel/r. When the bike is cold you should get a reading of 720 ohms, plus or minus 20%.

[CaptonZap]

You stick one probe in from the back of the connector to make contact at the connector, and just touch the other probe to the frame in a spot where you can get a good ground.

One caution here. Not all probes are pointy enough to get into the back of the connecter and down to the metal. You might try sticking the pointy end of a safety pin in there, to make sure that you are touching the metal.

[Chicagoxs]

You do the test with the ignition on, but not running. With the connectors in place and the ignition on check grey to ground (12v), white/red to ground (12v), black/white to ground (6v), orange to ground (12v) and red/white to ground (12v). You stick one probe in from the back of the connector to make contact at the connector, and just touch the other probe to the frame in a spot where you can get a good ground. It's also a good idea to get a reading on the battery, just so you know how much voltage you've got to start with.

I doubt it's causing your troubles, but while you've got the dmm out you might as well check the resistances to the pickup coils too. With the ignition off, pull the four wire connector off the TCI, and connect a DMM to the contacts inside the connector. They're in pairs - two wires go to one pickup and the other two go to the other pickup. Check wht/r to wht/gr and yel/gr to yel/r. When the bike is cold you should get a reading of 720 ohms, plus or minus 20%.

Thank you, will do that when I get home today!

[dbeardslee]

And while you're checking stuff, one other thing. Might as well check the continuity on your feed wires from the TCI to the coils. Pull the big connector at the TCI, and pull the connectors off the coils (one at a time) and check the resistance on the orange, grey, and red/white wires by putting a probe on each end of the wires. You should get the same reading you get when you touch the probes together. If you see resistance on the wires it's generally an indication that your connectors need some attention.

[motoman]

Like the title says coil A keeps going bad. I rode the bike for about 15 mins once I first got it running and a coil went bad. I replaced it with a manga coil. All was good. I took the bike out for an hour the other day and the coil went bad again. It reads fine on the post with the connectors. But when checking the secondary it gets nothing. I almost killed the bike leaving a light, and that is when it went bad. It was fine for the whole time until I almost killed it. When I almost killed it the bike nearly turned off but I saved it, and it was bad immediately after that. What could be causing this coil to keep going bad? I am thinking bad regulator possibly? Thanks

Mixing coil brands CAN be problemmatic causing coil failure, even with those used to replace. They SHOULD ALWAYS be replaced in pairs. The OHM difference, or low OHMS if any is also problemmatic. INnmy professional opinion, .2-.3 ohm loss or increase condemms the coils.