No spark on left side

Roger

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Hey everyone I'm sorry if this comes out wrong I'm a little frustrated..
So I was cruising down the road going about 45 and all of a sudden I lost spark my bike shut down when the bike finally stopped I kicked it over a couple times and you got nothing I took the left coil wire off the plug and put my finger in it kicked it over no spot I took the right side off put my finger in it kicked it over and God's zapped so just to see what would happen I changed the wires going to the coil wire and now I got spark on the left side and not right so it's obviously not the coil what would stop the left side from getting a signal.... So I left the bike on the side of the road for a couple hours came back with the trailer to pick it up just for s**** and giggles I kicked it over and it started and shut it off and put it in the trailer brought it home couple hours later tried to kick it over and I didn't get nothing somebody please help me thank you
 
So your carburetors really did have an electrical problem. Happens all the time. So when it started before your put it on the trailer was it running on both cylinders? If not one of your pickup coils is not working or one side of the magic box that times the spark has decided to go to Aruba for vacation and may or may not decide to not come back. Or you have a wiring issue. Go thru the wiring and clean all the connections on the offending cylinder side. Look for pinched wires, dirty connections, ground faults ect. The spark box on this one may just have a bad ground or dirty connections but the only way to find out is to start and one end of the circuit an work your way to the other till you find the problem. I am not learned enough with the Ing control system on this bike to give you detailed instructions but I'm sure someone on this forum is. Here is a wireing diagram for an 81 start at the pickups and check everything till you get to the coils

xs400-jpg.4628
 
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Only one pickup - it is on the diagram labeled "Pick up" with a 3-connector plug on it.
To check the connections you will need a multi-tester on the ohm setting to check continuity between plugs. If you don't have a meter, get one and look at some YouTube videos on how to do continuity checks on wires. If the plugs and wires check out between the pick up, the Ignitor unit and the coils, you probably have a faulty ignitor (also known as the TCI).
The plugs don't fire simultaneously.
 
Yes I have a multi meter and I know how to run the tests..I appreciate that when I get home I'll see what happens... If the plugs don't fire simultaneously then the fire at the same time??? I'll get back to you after I check it out thank you very much for your help
 
The way this bike fires is:
The left cylinder fires, the crank rotates 0.5 turn and the right cylinder fires, the crank then rotates 1.5 turns and the left cylinder fires again repeating the cycle.
 
I did the continuity test and I have a good connection all the way to the ignitor unit... Would it be possible that my pickup is only half working because I pulled the cap off and there's two points that pick up?????
 
You can check the pickup coils by measuring resistance. The connector plug is under the gas tank. Checking resistance between the Black and Red and Black and Blue should read 700 +/- 150 ohms.

If the pickup coil checks out, your battery is good, your coils test out good, your plugs are properly gapped and good and your wiring checks out, then the last thing is your TCI is bad.
 
A low battery would make me lose spark on one side??? My battery is pretty low I'm not with my bike right now because it's raining like a siv out side.. Thank u so much for the help I know what I'm doing for the most part but electrical aggravates me lol
 
At idle, you can have dips in voltage from the alternator and the battery will act as a buffer for that. At higher rpms, and with a properly working charging system, it's not a big deal as the output will be above 13.8 volts.
 
I Actually just had a similar problem with my 1980 xs400G. For me I lost all spark, and it turned out to be a bad connection at the ignition fuse. But along the way I picked up a few things. Get a test light or voltmeter. Remove the gas tank and disconnect the connection from the coil to the wiring harness. When the key is turned on you should have a solid 12v at the red/white wire. The orange wire will get 12v everytime there is supposed to be a spark, hold a test light against the orange wire terminal while cranking the engine, it should blink.

This will help you tell which direction to look for no spark.
 
Also if you don't have 12v to the red/white wire unplug your igniter unit (The red/white wire gets 12v directly from the kill switch, and the igniter unit gets a 12v source of power from the same wire) If you then have 12v now at the coil then chances are the igniter unit is grounding out internally.
 
Also if you don't have 12v to the red/white wire unplug your igniter unit (The red/white wire gets 12v directly from the kill switch, and the igniter unit gets a 12v source of power from the same wire) If you then have 12v now at the coil then chances are the igniter unit is grounding out internally.
Thank you for the advise I'm going to do that because I can't see how I'm getting spark on one side and not the other I was told if the cdi is bad then I wouldn't get any spark so I'm going to go ahead and try what you said n I'll let u know how it's good.. Thank you very much for the advise
 
Also if you don't have 12v to the red/white wire unplug your igniter unit (The red/white wire gets 12v directly from the kill switch, and the igniter unit gets a 12v source of power from the same wire) If you then have 12v now at the coil then chances are the igniter unit is grounding out internally.
Ok so am I supposed to have 12v on the orange or grey wire when I'm not turning it over??? Or should it only have power when turning over???
 
the red wire gets power constantly once the key turns on. Depending on the crankshaft position you might have power to the orange wire with the key on, but power will blink on and off when cranking over the engine.

this diagram is for a antique car but same principle. On our bikes the "distributor" is attached to the top of the engine right in front of the fuel petcock. If your bike is older than 1980 it has mechanical points, if newer it has electronic ignition. As the engine spins it sends a signal to the ignition box letting it know when each individual cylinder is at top dead center and ready to ignite the gasoline, from the ignition box it cuts power to the coil. thereby grounding the coil as the electricity tries to find a ground source which is the spark plug.
If any of this info is wrong anyone is free to correct me
 

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