My name is Matt and I do most mechanical work myself on all vehicles and atvs when I have the time. Electrical stuff kinda blows my mind though. I need help.

The engine cranks but I have no spark at plug

I did the tests that you suggested to securejohn and I didn't get any ac voltage at all no matter the situation. I did the kill switch test and it did not zero, is that correct? What is the difference in the stator and the magneto?

 

Hi Matt,

It would really help if you not only did all the tests but reported the results as well. This is especially important when electrical stuff is not your forte. Many of the tests reinforce one another (if they're done right) and that is a good piece of info. If they don't reinforce each other then that's a red flag and we can dig in deeper.

For example, you say that you got no AC voltage at all anywhere. But equally important are the resistance measurements to ground on the same wires. You need both to make a good diagnosis. What brand meter were you using? What scale(s) were you on?

On the kill switch test you say "it did not zero". I need more detail. Were you measuring ohms? What scale? When you turn on a kill switch (to the kill position) does it change?

Magneto and Stator are often used interchangeably. One could argue that there is a difference based on points/condensor ignition versus CDI ignition, but so many people have muddled it up that argument has lost a lot of meaning.

 

using a Cen-Teck digital multimeter- cheap but hopefully good enough.

Kill switch test Method 1 - no spark

Kill switch test Method 2 - run position - meter in 200k ohms setting - infinite

wiring connector test

ac power ignition pin to ground pin - meter 200k position - infinite

timing pin to ground pin - meter in 200 ohms setting - 124.6 ohms

ac ignition power pin to ground pin while cranking - meter 200 vac setting(lowest setting) - 0 volts

timing pin to ground pin while cranking - meter 200vac - 0.1 volts mostly showing 0.0 volts but would jump to 0.1 some


output side of CDI

Ignition coil pin to ground pin - infinite on all meter settings

CDI plugged in - meter in 200 vac setting - kill switches in run position - ignition coil pin to ground pin - 0 volts

 

I have several of those Centech meters. They're crap mostly, but they do work (except when they don't), and its a cheap way to monitor several voltages simultaneously. I bought eight of them and still have 5 that work a year or two later. I have a good meter too for precise measuring, but I can't afford eight of those...

Your AC Ignition power wire power winding is open and produces no voltage. Note the wire color in the harness on that pin. Go down to the stator wires where they emerge from the engine side cover. Find the same color wire there on the wiring harness side. That will be the other end of the wire from the CDI connector.

Now look at the engine wires from the stator and note which wire hooks up to the AC Ignition Power wire in the harness. Unplug it and measure the resistance of that wire to engine ground (engine side wiring). If it is still open your stator is bad. If it isn't your AC Ignition Power wire from the stator to the CDI connector is open.

 

Testing both wires, the wire from the stator to cdi and the wire going into the stator, they both show closed, they zero out on the 200k ohm setting.

With the meter on the 750 vac setting - negative terminal to engine ground and positive terminal to ac power wire - while cranking the engine - no voltage.

Should there be a dc power wire going to the stator?
I have the #3 stator magneto that is on the sunl website.

Stator Magneto 03 for Chinese 50-70-90-110cc Engines - Sm272-03 - 50cc - 125cc Stators - Stator Magnetos - Electrical Parts - In Stock at Sunlpartsonline

 

My comments embedded in blue...

 

Sorry I did all the tests again and it showed the same as the first time. I must have done something different? Sorry for the confusion. Thanks for all your help. I ordered a new Stator and i will let you know if it works

Thanks again for all your help!!!!! It is very much appreciated!!!!!

 

Even seasoned techs get caught all the time by measurement error. It's part of the process - you check and re-check, move forward a bit and then re-check again....

Please do let us know if the stator fixes it...

 

The stator fixed the problem. Thanks for all the help!!!

 

Awesome.