No spark on left side!

[ghoulgang]

Hey All.

Update since my last thread (about a stripped idle stop screw): fixed the strip with Teflon tape. Bike ran well for a few days, then got progressively harder and harder to start.

I thought it might have been a timing issue or a points issue or something so over way too long of a period (weeks - and the weather has been stellar ) I checked the condition of the points, re-timed the engine (thanks BCware for the video!) and such. Was about to pull the carbs when I realized I hadn't even checked the damn battery- sure enough 7volts. Charged it up and now it starts first kick but only the right side is firing.

*!* while I was fiddling with the points and the timing I pulled the plug on the right side tested for spark and got it. I went in the house to get something and my friend (rides an xt) had pulled the left side plug (without me telling him that it was almost stripped and you had to be VERY CAREFUL and use your fingers). "What did you do?!" - "I just pulled the plug? So what" me: "were you careful?" - "no, not really" me: "did it come out easily?" - "no, not really haha" ... More on this later.

Anyway after he pulled the left side plug we saw spark there as well. Fast forward two weeks and with a full battery the right side fires right up but the left side has NO spark.
I pulled the tank and tested the coil and the primary and secondary windings (left side coil) were within spec. - again, thanks for the photos BCware.

Any ideas of what it could be? All the connections I could see seem to be connected. Could it be that I did the timing wrong? Shouldn't that still give me spark just at the wrong time? I don't see any spark at all while the bike is at idle and the left plug is grounded against the cylinder head...

Please help I'm dying to ride

 

[arfstrom]

my bike may not have points, but I had a similar issue, and new plugs/wires/Caps all the way around fixed it. perhaps you can trim an half an inch on either side of the wires, just to get the spikes down to fresh wire. after all they are just spun on. (both sides of each wire)

 

[ghoulgang]

I cut down the left side wire, and fitted a new cap and new plug, still no luck (NGK 1ohm camp with iridium plug) put a new non-iridium bpre7 plug on with the old cap, still no luck, tried every combination of the new and old caps and both kinds of plugs and still no spark.

I followed the spark plug wire up to the coil, and it didn't look like that wire comes out any easy way, it didn't really look like the type f thing that was designed to come out... Interestingly it doesn't look the same as the coil test diagram in the Haynes manual, although it DOES look like the photograph of the coils on the previous page in the same manual?

Looks like these ( not my image)

Like I said I measured the winding resistance and they were both in spec...

Any help guys?

 

[ghoulgang]

Anyone know if I can run irridium plugs (bprex7 or whatever) with 1k ohms NGK caps and performance wires with these coils on a points ignition 1978 xs400 e?

 

[drewpy]

are you getting 12v to the coil with ignition on?
could be ignitor box fault

 

[MechNewb]

Try switching the coils from left to right to rule out the coil being a problem.

 

[ghoulgang]

Any advice on how to change the wire on these type of coils? (pictured above)

 

[16VGTIDave]

To the best of my knowledge, the wire is part of the coil with that design. Unless it has physical damage, chances are that the wire is good. The end that the boot connects to may need to have a few mm's trimmed off to get to clean wire.

Any attempt to splice a new wire on will probably result in sparks leaking and misfires.