How easy is it to wreck a coil? Did I do this? Twice?

[sam000lee]

I'm almost done putting my old GS450 back together with stuff from a parts bike and started it up for the first time a week ago. I cleaned up and redid a bunch of the wiring around the R/R which I am fairly confident is all correct but am having spark troubles. Here's where I am at:

1. I started the bike up last week for the first time aft to find that it was only running on the left cylinder. I have two sets of coils so switched out the right coil, no difference. Put in new plugs, still no difference.
2. I thought maybe it was a carb thing and the right carb wasn't getting gas or something, but when I switched them out with my other pair (that I know should work at least okay), neither side was firing. So I checked for spark and realized I wasn't getting it on either side.
3. I took my spare LHS coil and put a spare plug in it and grounded it to the engine. The bike started immediately, running only on the RIGHT cylinder but the left external coil was getting great spark. I figured problem solved, shut it off, mounted the tank but when I tried again it wasn't sparking again.

When I test the potential from the (+) battery and stick the other probe of my voltmeter to the coils I am getting 11.57 volts. Not the full 12v but not too bad either. The external coil (the one that I got the bike to start up on as described in #3) only shows 5v or something, which confuses me since it seemed like that was the `good one'

I also have a spare ignitor that I switched out, no difference. I'm wandering how easy it is to `fry' a coil or something, and if it's possible that theres something in my wiring that is just destroying the coils when I start the bike up and run them for a second. I even double checked my timing.

I havn't done the relay mod yet so will do that this week, but still can't explain why I would be getting spark on the left, then none at all, then on both sides when I switch out the left coil, and then suddenly nothing again with no apparent changes.

Thanks in advance for any insights.

[JTGS850GL]

Kind of hard to destroy a coil. My bet is a wiring issue.

[Brendan W]

My guess is that you have trouble at the coil supply plug. The pins may appear clean but how are the cores of the wires round the back of the connectors. The ignitor plug does similar things when bad but as this problem is changing as you switch in and out coils so I reckon the supply plugs are the place to start.

[sam000lee]

I thought about that and was doing a fair amount of wiggling the connector to try to see if that changed anything. The strange thing to me is that they both came on and then cut out at the same time. If one coil isn't connected, it shouldn't affect whether the other one is firing, right?

Either way the relay mod will bybass that connection so I'll see what happens after I do that.

[sam000lee]

For the coil relay mod I have three questions and I'm referring to this diagram.

1. Which of the two wires going to each coil is power? What does the other wire do? In the diagram my guess is that the yellow is power.

2. Which wire gets hooked up to the 'switch'. I was under the impression that it was going to come from the igniter unit but this picture suggests it should come from the kill switch
ign_coil_relay_upgrade_diagram.jpg
3. Is it best to hook the ground to my SPG?

Thanks!

[posplayr]

For the coil relay mod I have three questions and I'm referring to this diagram.

1. Which of the two wires going to each coil is power? What does the other wire do? In the diagram my guess is that the yellow is power.

2. Which wire gets hooked up to the 'switch'. I was under the impression that it was going to come from the igniter unit but this picture suggests it should come from the kill switch
[ATTACH=CONFIG]45330[/ATTACH]
3. Is it best to hook the ground to my SPG?

Thanks!

1A.) Orange/White (O/W) is the switched Ignition Power.
1B.) The other wires ground teh coil and release the ground at the proper timing to initiate spark.
1C.) O/W
2A.) The diagram is correct follow it.
2B.) To complicate things you could power your ignitor (it is also on O/W) from teh relay 87.
3) Does not matter much but SPG will do just fine but any B/W will work.

[jdvorchak]

Coils are easy. There are only three connections to a coil. 2 small wires are the "primary" and the spark plug wire is the secondary.
For the coil to work you have to have 12v from the ignition switch to apply power to one of the small wires and should go to the same connector on both coils. The other small wire has to be "triggered" from the ignition ignitor or in the case of points to the points. So usually there are 3 colors of primary wires. Lets say you have a black wire that has 12v from the ign switch. It would connect to the same relative post on both of the coils. The other two colors are blue and yellow. Those would hook to the other post on each coil. They are the timing triggers to each coil, lets say blue for left and yellow for right.

All the relay mod does is bypass the ignition power wire and route it to the battery instead of through the ignition switch. The remaining wires (triggers)to the coils remains intact.

I hope I didn't confuse the issue for you.

[sam000lee]

Got it, thanks all. I had cut the O/W wire in between the ignitor and kill switch and put the kill switch end to my switch. Was getting funny results. I put it back together and took the original O/W that comes from the ignitor/killswitch and used that to switch the coil and now its working great.