Hello there I just got my son one of these 50cc atv. it is used and i can find any info about it.Its a U Like, i beleave. It was running fine but when i moved the wireing going into the stator it stoped and no I cant get a spark, My cdi box only has 4 pins so i doint know how to check the kill switch.
I only moved the wires so I could tuck them under the clip and out of the way.
As well do i need a puller to get the cover off so i can check the stator?

Thanks for any input on this
Eric

 

if you moved the wires and it stopped working sounds like you have a short or a broken wire should be kind of easy to find I would start were you moved them, As for the kill switch get a multymeter and use the continiuity setting. It will sound when the switch closed or pushed in and stop when you release it. Thats were I would start hope it helps

 

Eric,

Four pin CDI systems are much different than the more common 5 and 6 pin CDI's. All CDI's run on a fairly high voltage supply (100-300 volts DC) which charges up a large capacitor, then at the proper time dumps the charge on the capacitor all at once onto the ignition coil primary. Most CDI's get their high voltage directly from its own high voltage winding wound on the stator. Your CDI gets its high voltage from a DC to DC switching power supply inside the CDI which steps up the 12 volts from the battery to the couple hundred volts required to drive the ignition coil primary.

I don't have a picture of a four wire CDI. Airmobile101 has the following picture on his personal album page showing the connections:

ATVConnection.com ATV Enthusiast Community - AIRMOBILE101's Album: Some pics - Picture

BLACK=12VDC/HOT
BLUE/YELLOW=Trigger PULSE
BLACK/YELLOW= TO COIL Primary
GREEN=GROUND

You said you were messing with the stator wires when this stopped working. The only connection from the stator to the CDI is the trigger pulse wire. Look very carefully at the trigger wire coming off the stator. It will usually go through a connector of some sort near the stator and then off to the CDI. That is the most likely failure point. If you find your wire colors are different from the ones Airmobile101 published, then identify the CDI pin that is the trigger wire, then note what color wire plugs in there. Then look from the same color near the stator.

Another approach is to unplug the CDI and measure the wiring harness pins for proper operation:

1) +12 volts: Should be +12 volts when the ignition switch is on, and zero volts when the ignition is off.

2) Trigger Pin: Should measure 0.2 to 0.5 volts AC to ground when the engine is cranking (note this is AC and not DC volts). Another test: Measure the resistance of the trigger pin in the wiring harness to ground (do this with the engine stopped). It should be about 140 ohms.

3) Ignition Coil: Measure tthe resistance of this wire to ground with the engine stopped. It should be about 2 ohms.

4) Ground: It should read zero ohms to ground.

Kill Switch: There are only a few practical ways to shut down the CDI and kill the spark. I don't know how your quad does this, but here are the ways:

A) Disconnect the 12 volt power to the CDI.
B) Disconnect the CDI ground wire.
C) Short the Ignition Trigger pulse to ground
D) Open up the trigger wire connection from the stator to the CDI. In this case the switch would have to be in series with the stator output on the way to the CDI module.

By going through the tests #1 - 4 above with the kill switch in both positions you should be able to figure out how the kill switch is wired up.

 

one last thing ask lynn Edwards she is the residant gooroo of the electrical world

 

Thank you for the helpfull info but I doint understand if my cdi has only 4 pins it needs a battery to run?
becouse I got it without a battery in it and it started and ideled fine. would it even run a cdi 4 pin without a battery? or is there something eles going on.
Ya i see some open heavy wire going under the flywheel but i know its not the trigger wire. My wire colours are the same as the pic in the link u sent me.
can u also tell me if i ues a backward thread puller to remove the flywheel of can i just use a automotive puller to get it. Thanks Eric

 

How did you start it without a battery? Kick start? Pull rope? Did you jump it to another battery?

Once the quad starts the battery charge winding in the stator and the voltage regulator will keep the 12 volt bus powered up and running. You dont need a a battery other than running the lights when the engine is stopped, and turning the starter motor during the start up phase.

If you measure the pins on your CDI and you find that you get 12 VDC on the power pin when the ignition is on then you have a 12 volt powered CDI.

The trigger winding in the stator is a very small pickup sensor which is always mounted close to, but outside the flywheel. It produces a very narrow +/- pulse pair once per revolution. I don't remember which way around it is - I think the positive pulse arms the CDI, and the negative pulse following right after fires the spark. It could be the other way around. If any one needs to know exactly I could look it up and post it. The heavy wire under the flywheel is the battery charge winding(s). If you have a high voltage winding for the CDI it will be a coil with 1000's of turns of fine gauge wire (also under the flywheel). Some DC powered quads have the high voltage windings and just don't use it. Otheres just don't have the high voltage winding.

Re: Pulling the flywheel: Is your engine a GY6? there are pullers for those. If it is not then I don't know. I'm good at electronics. I'm so-so at mechanics. Others may be better at answering this than me.

 

One small correction: I'm a "he" not a "she" . I'm 55 years old, married with two grown kids.

My name gets me into this situation a lot. I should probably put this in my personal info section. No big deal, just don't want any misunderstanding...

 

ok i will be doing the tests that you have laid out in your answer today and post back. It is a pull start.
I realy doint know what the motor is in it I cant find any numbers or tags on it anywhere. Thanks again Eric.
lol thanks for clearing up the he/she thing.

 

ok I started doing some of the tests and seemed to be getting no where so removed the flywheel and found that a yellow wire has broken off the stator so i started looking for a new one but could not find any that are like mine. I will try to post some pics of it but it looks like a big coil of wire with the brushes ridding on the top of it. the brushes are inside the flywheel, anyone know what kind this would be?
Thanks Eric

 

The "brushes riding on top" has me completely baffled. I think some pic's would help.

Inside the flywheel is where the battery charge windings lie, as well as the high voltage winding that poweres the CDI on most chinese quads (which I don't think yours has, and you didn't report seeing anything like two different coil configurations).

So lets guess for the moment that your battery charge winding (which feeds the the battery circuitry to keep the battery charged) is broken (the yellow wire), and you reported earlier that your quad doesn't have a battery. Therefore there is now no power source to make the 12 volts to run your DC powered CDI. So when you pull on the rope, so you will get no spark. I think you may have found the problem.

So is there any reason why you can't just fix the broken wire by soldering it back onto whatever it came off of?