No spark! I need theories an ideas

Hello, first of all, I have 2 1982, Yamaha XJ750's, the one is a solid running bike, everything works, the second one I'm restoring and giving it a new life. I went through the whole engine and now I have it back together, but now I have a problem, I cant get it to spark! I've swapped so many parts off of my working bike and I still cant get it to work. I've swapped the TCI, Dioid, Coils, Regulator, I have a brand new points assembly, I took apart the generator (stator), everything works there, I have power coming to everywhere in the wiring harness, I took off and cleaned all the grounds, but now I'm STUMPED! I don't even have any theories anymore.... do you have ANY ideas? At this point i'm quite certain that its something stupidly simple that I just haven't thought of, seeing how I've basically swapped all the parts off of my working ignition system.

Thanks for any ideas that you have!

 

You could try removing the black/white wire from the TCI and seeing if it has spark then. That wire is grounded by the safety circuits to stop spark, removing it will show if the problem is in that area.

Check for power at the red/white with the ignition on. This confirms power is getting to the TCI via the fuses, ignition and kill switches.

 

Ok, I'll do that! Thanks allot! I was out of ideas...

 

There is a troubleshooting procedure in the manuals which works. You need to go step by step and only change one thing at a time to be sure. I would use a multimeter and check continuity and resistances. A safety system shut off being active is also a good possibility. Also double check your wiring connections so that nothing is loose or corroded. You must have a good as in fully charged battery as well or the starter motor will suck down all the voltage and your coils won't get enough to spark.

 

DarkFibre, I did what you told me to do and I disconnected the one wire off the TCI and what do you know, it fired up! We still have to sync the carbs, but she runs! First time in 19 years! Thank you so much for your help! I really appreciate it! If I ever meet you, I'll buy you a steak dinner! lol

 

That your Bike fires-right-up with the Safety Circuit disabled is a relief because now you got it running.

All you need to do is check a few things and find-out what prevented the OK Signal to the TCI.

1) Side Stand Switch and Activating Rod.

Easy.
Remove the screws mounting the switch.
Pull the Rod out from the drilled-thru "Tunnel" at the Hinge Bolt.
Clean the Rod Sections
CLEAN the Hinge Tunnel and twist a rolled-up bit of 400 or 600 Sandpaper in there to shine-up the drilled hole again. Lube. Waterproof grease.

2) Switch.

Simple.
Shoot some Electrical Parts Cleaner into the guts and FLUSH-out the Case.
Douche that baby clean.
Isopropal Alcohol will do the trick. Unscrew the Cap and put a small hole in the Bottle Seal and squirt until what comes out is as clean as what goes in.

3) Clutch Switch.

Easy as Pie.
Press on locking Tab.
Withdraw Switch.
Hold switch body with index and middle finger.
Work "Plunger" with Thumb.
Douche the heck out of it. Lube with SMEAR of H2O proof grease or HD Silicone.

4) Safety Relay.

Like takin' candy from a baby.
Meter.
9Volt Battery and Test wire clip-on.
Listen for and feel for a click.

You want to get back to the Plant not starting with the Stand down.
And, ...
You don't want the Bike to BOLT and START without it being in NEUTRAL ::r::: the CLUTCH LEVER ---> PULLED!

RadioShack - (c)

 

I really appreciate the tips! I will go through and check the safety's tomorrow, I'm sure with your help I'll pinpoint the issue! Thanks again!