Only one side firing!

[Yusiro]

Hello All,

Hopefully someone will be able to help me. I have a 1982 xs400 heritage special that I rebuilt two summers ago (with the help of the fine members of this forum) which was running great... up until last week. About 200 yards from home she started sputtering, and running really rough, until dying as I pulled into the driveway.

Since it has rained every day since, I haven't really bothered looking at whats up... but now it's sunny and I want to ride!

Long story short, I figured out that only one side was firing. The left was not. Tested the spark plug - Ah ha! no spark. Problem solved - or so I thought. Put in a new plug - still no spark . I tested that plug on the other side - nice strong spark.

So I figured it might be the ignition coils (I believe that's what they are called, right under the tank at the front). Just to be sure, I took the power from the right one, and put it into the left. Low and behold - spark on the left.

So basically I'm figuring it's somewhere in the wire that goes to the left ignition coil.

Now I'm stuck - I don't want to start ripping wires apart if I don't have to.

Does anyone know what it could be, and how to fix it?

If I need to unwrap all the wires and look for a break, so be it - but I'd rather not do that if it is not the issue.

Any help would be greatly appreciated!

Thanks in advance,

Yusiro

 

[JARichmond]

Check for continuity throughout the coil. Primary should be around 4 Ohms of resistance, secondary should be a handful of kOhms (~9k if I remember correctly). If there is infinite resistance in either coil, there's your likely problem. If not, consult a wiring diagram to find which wires run to your coils and check for continuity across any uncovered parts of your wires. Once you find the discontinuity, clean the connection, repair if necessary, and test. Continue searching if it doesn't fire up on that cylinder.
Best of luck

 

[Drewcifer]

download pdf, find coil testing page, use multimeter, test coil. I have used ones and a new ones if you need to buy them. Got them from Mikes xs.

 

[Yusiro]

Hey all,

Thanks for the help with this. I tested the continuity through the coils, and all the way down both sets of wires to the large clip that goes into the TCI unit under the battery box. Everything is working as it should... which leads me to believe that the TCI unit has now failed. Based on the shop manual (Hanes) the TCI (aka CDI) unit, once it's decided that is indeed the problem, cannot be repaired and needs to be replaced.

Now, as I said, it is a 1982 xs400 heritage special. I believe it is the SJ if I'm not mistaken. Does anyone have any experience with this part? There are several on ebay, and I might be able to get one on the forums here, but first want to make sure there is a good chance that it is the issue with the bike.

If anyone could offer any thoughts or experience on it, that would be great!

Thanks