‘85 250sx no spark

[MikeD70]

https://youtu.be/LUftRXfItHk

Video of meter connected to ignition coil wires while cranking.

[gimmeamidget]

That doesn't appear correct. I have only used a tester light but the light was lit the whole time but fluctuating between dim and bright. I would have expected to see the meter hover between low volts and 12v. It appeared you may have had 12v but very seldom.

[gimmeamidget]

Kind of looks like symptoms from a bad ground or could be bad cdi. I would double check all grounds and make sure connectors are good and ground ohms out at 0. Do you know anyone with same bike you could swap cdi with?

[Doug8765]

I think the crankshaft that runs the stator breaks by the stator it happens


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[MikeD70]

https://youtu.be/3YDjyYc2ZKk

if you bought a new coil and you still dont have spark then theres not going to be any voltage going to the coil. this is why if the exciter coil is good i think you should test the pulse generator. if the pulse gen checks out the cdi or a broken/grounded wire is about the only thing left to rule out.
what was the reading on the exciter coil?

if the exciter is good then you have voltage going into the cdi. the only possibility now is why the cdi isnt passing the voltage along to the coil.theres 2 likely causes. 1, either there is a kill wire grounding or a bad kill switch(which is why we unplugged the kill switch to rule it out) or 2, the pulse gen isnt sending the message to the cdi.

Now as for ruling out the kill switch and the key im not there in person so i cant say for sure but the wire coming off the cdi splits and goes to the kill switch and the key on/off you should be able to disconnect the wire from the cdi where it splits into two. its open circuit which means if the circuit isnt grounded it will run so if its unplugged you rule out the possibility of an issue past where you unplugged it.

let us know the exciter coil ohms and if the pulse gen is sending a pulse and we will go from there. im saying to use an ohm meter on the lowest setting because i dont think the voltage from a pulse gen will light up a test light(it may but 1-2 volts might not be enough and youll see the change on an actual meter while cranking)

Exciter coil ohms measured 317.3
Pulse generator ohms measured 330.9
Haven’t checked voltage on the pulse generator yet, will check as soon as I get a chance.

[MikeD70]

Kind of looks like symptoms from a bad ground or could be bad cdi. I would double check all grounds and make sure connectors are good and ground ohms out at 0. Do you know anyone with same bike you could swap cdi with?

Ill check all the grounds again. I only found grounds at the frame from the battery, a ground on the rear frame near the tool box (green wire) and where the starter grounds.

Unfortunately I don’t know anyone with the same bike to swap the CDI.

[gimmeamidget]

If you can pm me your name and address I can pull my Cdi off my 85 250sx....it's the single connector not the double connector type....and send it to ya to try if you could send it back after you try it. That way your not throwing money at it not knowing if that's the problem.

[MikeD70]

https://youtu.be/3YDjyYc2ZKk

Video of meter reading on pulse generator blue/yellow wire and green/white wire.

[MikeD70]

That would be awesome. I’ll pm you.

[lndy650]

ya looks like its gotta be the cdi the pulse gen is definitely good

[MikeD70]

I'm just wondering, the values given for the resistance measurement give one for ND and one for MITUBA (have no idea what this stands for), which value should I be comparing to?

[MikeD70]

I'm just wondering, the values given for the resistance measurement give one for ND and one for MITUBA (have no idea what this stands for), which value should I be comparing to?

UPDATE: I swapped out the CDI with one from another running bike, still no spark!

[lndy650]

ok so the exciter coil tested good, the pulse coil tested good, good wire and cap, new coil, and cdi off running 250sx. im thinking it has to be a bad wire somewhere. with this new coil what is the coil reading from the cdi plug is it still over spec at .4 or is it in spec now?

[MikeD70]

ok so the exciter coil tested good, the pulse coil tested good, good wire and cap, new coil, and cdi off running 250sx. im thinking it has to be a bad wire somewhere. with this new coil what is the coil reading from the cdi plug is it still over spec at .4 or is it in spec now?

I will have to double check the reading on the new coil. I got it on eBay, but it is an aftermarket one.

[lndy650]

i was thinkin it might be possible theres bad wiring if the reading is still high at the cdi plug but normal at the coil