I'm with kazafog. I'd do some measurements with a meter before making a determination as to why you don't have spark. Most ignition problems are *not* due to CDI failures. Meters are very inexpensive, and they are a very powerful tool. Yes, they do require some practice and guidance, but it is worth the effort in the long run.

Some things cannot be measured with a meter. But a lot of things *can* be measured. It seems to me that it would be worthwhile to use a meter to eliminate all the things is can be measured before just blindly changing things.

 

i already confirmed 100% its the CDI i'm just waiting for my fox racing 1 to come in ... do i have to change coil for a high performance 1 or will the old 1 work fine with the racing CDI? and i do have a multimeter and my dads a certified electrician so he knows whats wrong...

 

Your old coil is fine.

 

OK so i blew up another cdi i dont have a clue in hell as to whats going on... if someone can direct me that would be a great help. my stator is acting funny like 23 V ac at cranking... but it gets spark for the first crank until i try again and then there is no spark...

 

Is this the 125cc quad with the 5 pin CDI that you referred to in another thread?

How do you know the CDI's are blowing up? The reason I ask is that 5 pin CDIs are pretty bullet proof as far as damaging them from the external connections. I'm wondering if you have other problems which you are mistaking for CDI problems.

Where did you measure 23 volts ac? Is this the AC Ignition Power pin at the CDI (to ground)? Did you measure this voltage with the CDI disconnected?

What about the trigger voltage? Kill switch circuitry? Have these been looked at?

 

thanks for the reply i was already doing all the looking at earlier... just finished basically what happened was we took the entire wiring harness apart and we didn't find anything until we went to the tether kill and it was in non working order so we put the harness back together and then i hooked it all up and made sure all the connections were tight and now whats happening was, the cdi wasn't blown and i am getting 18v AC off of the stator before it entered the CDI and after the cdi i am getting 8.0v DC before the coil still no spark these were measured with the connections disassembled... me and my bud pushed the ATV in 3rd gear down my street to spin stator faster and i got 74.2v ac out of the stator before the cdi... and this was pushing like 20 km/h haha were young and lively... anyways still didn't get spark and all the wiring was monitored by my dad and hes a certified electrician but he doesn't know about the stator and cdi stuff hes been out of the trade for a bit and he was more factory wiring but can read all the schematics.. i'm 17 on Tuesday and i'm also in gr 12 auto so if u throw big stuff at me ill know what your saying. also there are stores 20 mins from my house who can get all the parts for these ATVs
UPDATE:
Trigger voltage: is 0.0v ac or dc but it was showing 1.4 v earlier forget if it was ac or dc and no power after the cdi now
and the kill switch system if fine now

and yes have referred to this ATV in another thread

 

The rear tether switch wires should NOT be wired together. That is the same as the switch being activated.

Yes. Yes I know you didn't say it was connected, BUT you didn't say it wasn't either.

Just trying to help.

 

I'm with armagh. I'm not sure about what you did with the tether switch, but the wires needs to be open (disconnected, or wires hanging free) in order to get spark. If you wired them together that will kill the spark.

18 volts AC is really low for the AC Ignition power pin measured to ground with the CDI disconnected - unless your starter is turning slow. The output of the stator is directly proportional to engine speed.

8 volts DC to the coil primary is not only wrong, it is impossible. This is clearly measurement error of some sort. You said the CDI is disconnected, yet there is 8 volts DC on the coil wire. If the CDI is disconnected there is nothing driving the coil input. Therefor it can be nothing other than zero volts. Even if the CDI was hooked up this still is impossible unless you are not telling me something (like smoke and fire was pouring out of your quad). 8 volts DC on a coil primary, with a coil primary resistance of 0.3 ohms, would mean your coil would have roughly 25 amps going through it. Your main fuse would pop. If someone wired around the fuse there would be fire.

I think you need to measure this again....

Good for you. I'm too old for pushing heavy things more than a few feet. I have to think of less strenuous ways to get answers. 70 volts AC is more than enough to get spark, so that is a good piece of info.

Good, but could I suggest that the best thing to do here is concentrate on making careful, accurate, and repeatable measurements with your meter. And then lets follow a methodical path. Bad data leads to bad conclusions, and that leads to blind alleys, proverbial garden paths, etc.

On the trigger voltage neither answer is good, and one is not particularly believable (the 1.4 volts something). And the "kill switch system is fine now". Exactly how did you determine that?

For the ignition system to work on your quad (5 pin CDI) you need to have:

1) Power to the CDI (AC moderately high voltage from stator)
2) A trigger pulse to the CDI (small signal AC voltage from stator)
3) The kill switch pin at the CDI must not be grounded
4) The CDI must have a ground (and the CDI must be good)
5) The Coil must be hooked up and working.
6) The spark plug must be working.

The first thing I would do in your situation is to take out the kill switch wire out of the CDI connector right at the CDI. Now there is no way spark can be killed by kill switch circuitry. Plug the CDI in with the kill switch wire hanging out. Test for spark. Do you get spark? If your starter is spinning slow due to a discharged battery use jumper cables and jump it your car. Do you get spark?

Then unplug the CDI and measure the AC voltage to the AC Ignition Power pin on the CDI connector while cranking at normal speed. What do you measure? Is this voltage repeatable?

Then measure the AC voltage at the trigger pin while cranking. What do you measure? Is it repeatable?

You must do these measurements while the starter is spinning at normal speed. Remember: Bad data leads to bad conclusions, and ultimately leads to frustration.

 

OK sorry when i meshured the 8v DC to the coil the CDI was hooked up then... and i found out the trigger is done and the stator has begun to quit...thanks for your help ill be replacing the stator soon ss for the CDI's i got 2 standard ones and a racing one on its way lol got a few spares now. And the theater kill was open when these test were done i meant we eliminated the tether... as for finding out what quit, the trigger kicks in and out and when it was sparking a bit the spark was weak and thin blue not fat haha.

 

So what ever happened???