Coil Gremlins

[EMS]

I posted this also in the proper area in the forums. Didn't know if everybody goes there regularly:









Maybe you guys have an idea:



One of my Sixes was running poorly and I found cold headers on 2 and 5. Quick diagnosis showed a sometimes very weak, sometimes non-existing spark on 2 and 5. As I still had a set of new, never installed Accels lying around, I decided to replace the coils. I also invested in six new plugs.

First try, bike runs like a charm. Take it to work for 15 miles, runs excellent in the morning. Park it and when I start it at lunch it runs poorly again. take it home and find headers 2 and 5 cold. Going over all wiring and connections and do some ignition checking, everything seems O.K.

Next thing, is checking the coils and I find the primary winding on coil 2/5 shows zero conductivity. Question: is this just a coincidence or is there something that can make the coil go kaputt?

I really hate electrical stuff.

[Tom Neimeyer]

Mike,

I am not a "electrics" guy either. I didn't think there was another electrical component that would "kill" a coil. I had a similar problem once and traced it to a pinched wire on the pickup plate. One of the three small bolts (with washers) that holds the ignition pickups was caught under the edge of the washer of the bolt and created a sporatic short.



Good luck and if worse comes to worse, I can send you some parts to swap out and try.



Cheers, Tom

[cbxtacy]

Or ask the wifey if you can buy another CBX to do electronic swaps with. A necessity for a good running CBX. I think I have a couple sets of stock coils, I'll look before I leave for CA later today.

[EMS]

Thanks guys! Parts are really not the problem. I have plenty of coils.( I may start a business: usedcbxcoils@hotmail.com ) Just want to make sure that I don't keep installing them after they fry for a reason I don't know. Only thing that I could think of, is excessive current to the primary wiring that could destroy it. But where would it come from?

I tested the primary circuit with a test lamp while cranking and it just shows the 3W light going on and off as it should.

[tab]

Could it be one of the spark unites that are mounted under the seat ??

Tom

[cbxtacy]

Try swapping the spark units and see if it fries another coil on different cylinders. Then you will have the culprit. Unless you have a 79 where the spark units are combined. That could pose a problem.

[CBX Steve]

EMS, this is exactly what I have with my baby CBX(550), but I have cylinder 2 & 3 off the same coil, but cylinder 3 is cold. Now I have put it down to a crook valve, found by removing the head. I did swap coils etc and still found #3 cold.



Interesting to say the least.

[broook]

Had the same problem a few years ago. Also with #2 & #4. To cut a long story short the cause was "somewhere" in the pulser compartment. Went through the coil, plugs, plug wires routine etc and nothing. I then took everything out of the pulser unit and cleaned everything up. When I reassembled the breakers I changed them around and bingo. Fired right up and no problems with it since. Must have been an intermittent ground somewhere I suppose.

[EMS]

Did the intermittent short in the circuit blow the coil???

[broook]

Did the intermittent short in the circuit blow the coil???

Sometime after all this happened I started the bike up one night in the shed and heard a slight ticking. I turned the lights off in the shed and saw a blue spark running down the side of the centre coil.



. The coil had split. I don`t know if this was a coincidence or not. It was firing on all six but the power was down until I changed the coil.

[EMS]

O.K., I checked everything. Continuity in all the wiring and the coils.

Resistance in the coils and in the ignition circuit between the pulser and the igniters. Could not find anything abnormal. Installed another coil and the bike is running fine again. Let's see how long...