No spark - something simple?

Okay I am pretty confident it won't be as simple as I would like but wanted to ask before I get too deep. 81 seca 550. Picked up recently, have never heard it run. As a result I have no idea if the front headlight functions. After a bit of trouble shooting I have all the other lights working (signals, tail and brake lights - horns too). Starter spins the engine easily. Assuming I have good grounds. There is no spark. I do have a functioning voltmeter. Just in case I attached a jump box to make sure I had sufficient voltage. (I have read at lower voltage the TCI will not function properly.) I have tried swapping TCI boxes and have both changed and disconnected the side stand relay at different points. Even tried changing out the coils just in case. Put new plugs in too. I did check wires into coils and had voltage there as well. It is an original fuse box - no broken clips and all fuses are the correct amps and check out for continuity. Changed out the diode in the headlight also as the one looked like it had failed. I do not see any obvious indication of the harness being hacked. Any thoughts anyone? Thanks.

 

Have you checked for any damaged wiring from the pick up coils on the left hand side of the crankshaft to the TCI input plug?

 

At a quick glance I did not see anything but will go back and check again. Thanks for the input.

 

I think there are orange and gray wires and one black wire. If the black one is damaged l think no pick up coils will be grounded.

 

Did you swap the TCI for a known good working one? Otherwise you could have two faulty ones..

 

The headlight will not come on till bike is running .

 

My XJ750RK has a battery that is on its last legs. If it has sat for a few days it will crank but doesn’t have enough juice to create spark and start. Had an XJ700N that behaved the same way. Just a little time on the battery tender is enough to get it to start.

In other words, there is a fine line between a good battery and a bad battery. Be careful not wasting time chasing down problems if you’re not 110% sure your battery is good and is fully charged.

I will get through the rest of the season with my XJ750RK battery but I know it’s pretty much done. At least I hope it makes it the rest of the season!

 

Latest update. So I have seen a spark. It is not what I would call a steady consistent spark but there is some life. I have swapped out the TCI, found a loose connection on the neutral switch (cleaned and tightened), faulty side stand switch (replaced), and I may have a bad connection "under" the TCI. At this point I am sure the battery is starting to fade. I will recharge it and keep going. A bit of an odd quirk, the voltage meter only reads about 11 volts when I attach a fully charged battery. Don't think it has anything to do with the spark issue but the meter itself may be bad. It would be helpful to see it jump up to roughly 12 when I turn on the key. I am sure I will find more.

 

I forgot to say that all your input is greatly appreciated!

 

Now you have a spark of sorts it's worth trying to jump start it with a charged car battery - especially if you have doubts about the battery you have. The Voltmeter is not so accurate on mine either but it should jump up when you get the bike started.