Not another no spark situation...

Hey guys looking for some help here. Ive gone through some relevant posts on the matter, still stuck. Here's the situation:

1982 XJ650 Maxim with 39k on the clock. No spark at any coil. Brand new battery, trickle charged for days producing a solid 12.8v. Bike is on the center stand, in neutral, kickstand up, clutch held in, nothing. Starter button turns the motor over great. Killswitch seems to be working (on OFF, starter button doesnt activate starter motor).

Ive tried unplugging that safety relay, no change.

I cut back the spark plug wires 1/4 inch, no change.

I got a used ebay TCI that the seller assured me was tested and working. Plugged it in, nothing.

Pickup coil resistance mid 600ohms.

Primary on the ignition coils within spec as well.

Two clues: With ignition on, I have approx 12v at each of the coil leads on both coils. When I hit the starter button, that drops to between 8-9v, but it doesn't flicker around like it does on my other bikes, just stays at 8-9v.

Also, the green neutral light doesn't come on all the time. Sometimes I have to flip the killswitch on and off to get the neutral light to come on. When it is on, or isn't on, no difference in performance, the starter motor turns over fine but no spark anywhere.

Any insight would be very helpful.

Thank you

 

Whats the condition of the battery and fusebox? More history available? What lead up to the TCI swap?

 

Battery is new and charged up. Fusebox is the old tube style hasn't been upgraded yet, but its holding strong and I have good continuity throughout the fusebox and across each fuse.

History is sketchy, it passed through many hands before it got to me. But its a fairly clean bike, cleaner than most of my bikes. What lead up to the TCI swap is all of the diagnostic experiments I described above.

To me, the main problem lies in the fact that it doesn't seem like the voltage is being broken at the ignition coil to induce the spark. It just dips down to 8v and stays there. I thought at first it was the fault of my digital multimeter. However when I hooked it up to my kawasaki, my multimeter was able to read the voltage fluctuations from 12v to 1v as I hit the button. That's clearly not happening here on the XJ, and so I was wondering why.

 

Neutral light is obviously unrelated to TCI. Something odd about resetting neutral light with kill switch?? Don't have an answer on that one.

 

the tci box makes and breaks ground so if you unplug the coil wire that goes to the tci box, turn the key on and touch that coil wire to ground you should get a spark when you lift it away. just jiggle it on ground, don't leave it grounded for any length of time. you might have bad coils, there's a lot of that going around.

 

Thanks Polock, good test. I did indeed get a spark when I did this test. Does this mean that my replacement TCI is also bad? Or are there other components which could be causing the malfunction?

 

i'am doubting both of the pickup coils could be bad. 2 dead tci boxes seem a stretch. i'd take a close look at the wires and voltage on the tci box then jump out all of the safety circuits. how the kill switch makes the neutral light work is strange but if you jump it out, it's gone

 

Agreed, I thought all those things being bad was unlikely. What about the little magnet on the pickup rotor? Do they wear out after 40,000 miles?

 

is that a magnet? i never noticed it being a magnet.
look at the clutch switch and the brake switch one is N/O one is N/C.
check that the relays are the right ones in the right places. some fit in the wrong sockets