Good evening and thank you to anyone who has any thoughts on the subject. I know just enough to be dangerous but not enough to figure out this issue for my neice.
The machine is a coolster ATV, 125cc. I'm not sure what year. I would guess close to 2019. Below is the cdi we are working with. A 5 pin model. Below that I will put the tests I read were recommended and below that I will put the results I got.



Method 1) Unplug the CDI and remove the kill switch pin in the CDI connector on the wiring harness. The pin is held in with a spring tab on the pin itself. You'll have to probe into the connector and push this tab in order to extract the pin. Plug the CDI back in (kill switch wire dangling) and see if you have spark.

Method 2) Unplug the CDI. Turn on the ignition switch and set all kill switches to the run position. Use a meter to measure resistance in of the kill switch pin in the wiring harness connector to engine/frame ground. If the reistance is infinite on the 100K ohm scale then your kill switches/kill switch wiring are OK. If you measure zero ohms then you have a kill switch/wiring issue.

The other inputs your CDI needs to make spark are AC Ignition Power, and the Trigger signal. Do the following:

1) Unplug the CDI. In the wiring connector measure the resistance of the AC Ignition Power pin to the Ground pin. You should see 400 ohms or so. What do you measure?

2) Measure the resistance of the Timing/trigger pin to the ground pin. You should measure 150 ohms or so. What do you measure?

3) Leave the CDI unplugged. Set your meter to measure AC volts on the 100 volt scale. Measure the voltage on the AC Ignition Power pin to the ground pin while cranking the engine. You should see 40 to 80 volts AC while the engine is cranking. What do you measure?

4) Set your meter to measure AC volts on the lowest scale you have. Ideally this would be 2 volts but many meters don't go down this low. In that case use the lowest scale you have. Measure the voltage on the Timing Trigger pin to the Ground pin while cranking the engine. You should 0.2 t0 0.4 volts AC. What do you measure?

Now for measuring the output side of the CDI:

A) Leave the CDI unplugged. In the CDI wiring connector measure the resistance of the Ignition Coil pin to the ground pin. You should measure less than 1 ohm (but not zero ohms). What do you measure?

B) Plug the CDI back in. Set your meter to measure AC volts on the 20 volt scale. Set all kill switches to the run position. Crank the engine while measuring the voltage on the Igntition Coil pin to ground. Poke through the insulation of the wire if you can't probe the connector.

Caution: There should be moderately high voltage spikes on this wire. Make sure your fingers are not part of the circuitry. Don't touch the probe lead tips while doing this test.

What you should see is a lot of random numbers with lots of zero values as well. This is because the meter may catch all or part of the spark event voltage, with a lot of nothing in between. Describe what you see.

Note: Using a meter to measure this point produces highly variable results depending on the meter. What you really need is an oscilloscope, but most always a meter is all that is available. We have to do the best we can with what's available. Describe the meter results as accurately as you can


Here are the things I measured on it. The ones that didn't match the recommended values I checked multiple times so I'm pretty sure I'm reporting them accurately.

My Results
Method 1
No spark
Measureing at kill switch is 0.1 ohms in killed position and open in run position

Method 2

AC Ignition Power
Recommend: 400 ohms
Actual: 547 ohms

Timing/trigger pin to the ground pin
Recommended: 150 ohms
Actual: 548 Ohms

AC Ignition Power pin to the ground pin while cranking the engine.
Recommended: 30-80 VAC
Actual: 49-50 AC volts

voltage on the Timing Trigger pin
Recommended: 0.2-0.4VAC
Actual: 49-50 AC volts

Ignition Coil pin to the ground pin
Recommended: <1 ohm
Actual: 678 Ohms

voltage on the Igntition Coil pin
Recommended: varies from pretty high through 0 VAC
Actual: Bouncing between about 16.4 and 16.6 volts AC


The problem is that I'm not sure what these results are telling me or even if they seem realistic. I see the timing trigger matches the ignition power. So I'm guessing maybe the 2 are shorted together somewhere. Looking at the wiring harness I can't see any signs of damage.
Also the ignition coil seems to have incredibly high resistance but I'm not sure if one problem could cause both of these.
I am hoping to be able to get this running for my neice. I noticed that I could get an entire electronic ignition system on Amazon for like <$40 and I'm totally willing to do it if there is a chance it will resolve the issue. Anyway thank you very much for taking the time to think about this with me. I really appreciate it.

 

Whilst the $40 for everything seems attractive, there are lots of people on here who have done that and still no spark. Always best to find a fault and only use substitution as a last resort. I don't read those resistances as gospel, every different make/model has different readings, and I have known trigger coils to produce those high voltages and work fine. I would substitute the spark plug, it is a service item anyway. Check the coil wire, if you were checking resistance at the CDI pin to get that 678 ohm reading, is it the same at the actual coil? If not, that wire has a fault. If you still get a high reading then I would change the coil. If that doesn't fix it, next substitution is the CDI, then onward to substituting stator if needed. Put original parts back on if the new ones don't fix it, just in case your new part is faulty, at those prices, quality control is minimal.