I am very appreciative of the info and insight you share with others!!!

I have a Chinese 110 cc 1 1/2 yr old unit that ran fine and now has no spark. Changed the CDI and coil - nothing....
I have tried unplugging the kill switch wire in the CDI and no luck.

Based on information on the site: I took voltage readings at the CDI (5 pin) harness and have 0V powered on & 61 V cranking at ignition power pin, but NO Volts at ignition trigger while cranking; nor at the kill switch cranking with the CDI plugged in.
I do have another running 110cc ATV that I also took readings on (to make sure I was getting presumably accurate measurements) and got: 57 V cranking at ignition and 0.2 V at trigger cranking and all sorts of readings with the CDI plugged in.

Resistance readings on non running quad: 121 ohms @AC ignition power and 351 ohms at trigger pulse.
Resistance on running quad 152 ohms @ AC ignition and 367 at trigger pulse. Infinite ohms on both at the kill switch.

Would the lack of voltage at the ignition trigger indicate that this is an issue with the stator??
I have read that it is almost always a kill switch, wire, CDI, followed by coil and lastly the stator that tend to fail. The Stator is different on the 2 quads so I cannot try swapping those

Any thoughts or comments would be much appreciated!!!

 

It is very fortunate that you have two quads with the same style CDI to measure. Measuring voltages to and from the CDI are best done with an oscilloscope, but that is beyond the reach of most people. Meters are the next best alternative, but they have some major limitations. But we have to do the best with what we have at our disposal.

One of the issues is how well your meter measures the very non-standard trigger pulse waveform. There is always the question of whether the meter is messing up, or the trigger pulse is missing. By measuring two quads you are proving the ability of your meter to measure correctly. That is a big step.

I'm concerned about your report that you don't measure any voltage on the kill switch pin of the CDI while it is hooked up. This is wrong for any CDI I've seen. The kill switch pin voltage is usually the unfiltered half wave rectified AC Ignition Power pin voltage. You read 60 volts or so (unloaded) on the AC Ignition power pin, so you should see big voltages on the kill switch pin too. Please check that again because it makes no sense... But keep in mind that you must have all kill switches set to the run position when you do this test. If any kill switch is on then the kill switch is shorted to ground and you will measure zero volts on the kill switch pin.

I didn't see that you have switched CDIs between the working and non-working quads... Have you tried this?

Your resistance of the ignition trigger and ignition power pins sounds reasonable. Your ignition trigger voltage of zero volts is a red flag. It is unusual for the resistance of the trigger winding to be normal, and then the trigger output to be zero. It can happen, though it is rare. Three scenarios (but again each very unlikely) come to mind:

1) There is a shorted turn in the trigger voltage pickup coil: That shorted turn will not affect the resistance measurement in any appreciable way, but it will destroy the inductance of the pickup coil and produce no output. There is nothing that can be done about that except replace the stator.

2) The pickup coil is spaced too far out from the flywheel: The trigger pickup coil works by having a raised steel bump on the flywheel travel past the pick up coil outside the flywheel in very close proximity. There is a magnet inside the pickup coil that has its magnetic field "disturbed" by the close flyby, and this disturbance wiggles a the magnetic field on the pick up coil and produces an AC voltage. The magnetic field from the embedded magnet in the pickup is bottled up by steel shielding around it's perimeter so that it's externally projected field does not go very far from the open end facing the flywheel. It has to be able to see the raised bump, but it must *not* see the *huge* magnets inside the flywheel that power the AC ignition power and the battery charge windings just fraction of an inch further away. Those magnets are *much* larger than the pickup coil embedded magnet, so it is an engineering challenge to separate these two influences. Hence the "critical" gap between the pickup coil and that raised bump on the flywheel gap. Rule of thumb is that it should be 0.025" You should look at this...

3) The inards of the stator can get messy. Rust and magnetic debris gets thrown around and is attracted to magnets. The pickup coil is most vulnerable to magnetic debris. As it is attracted to and piles up on the trigger coil hot end (facing the flywheel) it further bottles up the output range of the pickup magnet. This is the same thing as moving the trigger coil further away (bad). Look at the trigger pickup coil and make sure it doesn't have an accumulation of magnetic stuff stuck at the face facing the flywheel.

I'm on the fringe here. These are all very rare situations, but also very possible. I would concentrate on repeating the more generic tests again (and maybe a third time too) and make sure they are all repeatable before concentrating on these very unlikely scenarios.

 

Lynn. Many Many Thanks! Your knowledge and insight is impeccable!!

Yes, I have tried swappi9ng the CDI's w/ no change.

Early this morning I opened up the kill switch housing on the handlebars and cleaned and retightened the each of the connections... Maybe that helped as I remeasured the non-running quad and got 54.3 VAC cranking at the kill wire w/ the CDI plugged in. (I also remeasured the running quad - w/ the spark plug wire off [to keep it from starting] and got 52.8 V cranking). That is good news, right?
After reading your response, I also remeasured the AC ignition = 57.1V and trigger readings= 0V. Running quad: ignition 58V / trigger 0.2. Thus all readings stayed relatively consistent

Not sure if this helps, but I also took readings from the actual stator wiring and yielded: Yellow wire 0.9 ohms; White 1.0 ohms; blu and white 121 (same color wire as trigger pulse at CDI); and black and red 353 (same wire as AC ignition power)
AND Yellow wire = 3.1 V cranking; White 4.0 cranking; Blu/white 0 V cranking; blk/r 59.4 cranking.

Lastly, I looked at the stator and did not notice anything that looked abnormal – but I would be the first to tell you that I probably would be able to tell. It is noteworthy that sometime shortly before the quad quit, one of the little threaded stator covers must have vibrated out – so it is entirely possible that some debris could have gotten in there.

Would this confirmed data lead you to think it is the stator?

 

It does sound like a bad stator to me. Take the stator off and inspect the trigger pickup coil for magnetic debris at the end facing the flywheel, then if nothing bad found replace the stator.

 

I am trying to fix a buddies sons little chinese 110 which has no spark. They wanted it fixed for his bday but I dont think were going to make it. I did the meter reading tests at the 5 pin CDI like I have seen posted on this site. First test I am supposed to have 45-80 VAC, and I have 35. Next I am supposed to have .2 -.5 and I have 0. Next I am supposed to have 450 ohms and I only have 330. Next I am supposed to have 150 ohms and I have 0. Next I am supposed to have 0 ohms and I have .4, and last but not least I am supposed to have .5 ohms and I do. Please help. If at all possible could you send info to my email,
Decoy-racing@hotmail.com. Thanks in advance

 

My comments embedded inside yours in blue...

 

Sorry for being so brief, my last post was my third with no responsee and I cant even find where they went which is why I wanted a email sent. The measurements that I believed I was supposed to have came from another area of this site that I cannot find now. Tell me exactly how to test the system the way that you want and I will get the answers back to you.
(My measurements were with engine cranking, ignition power pin to engine ground which I got 35 VAC, timing trigger to the engine groundwhile cranking I got 0 VAC, net I measured in OHMS (2000 scale as directed) Ignition power pin to engine ground in which I got 330 ohms, and the timing trigger to the engine ground I got 0 OHMS. Next I reset the meter to the 200 OHMS setting and measured the ground pin to the engine ground where I found .4 OHMS, and ignition coil pin to engine ground I found .5 OHMS) None of that matters I guess if you cant read it so Give me the step by step and we will do it your way. Thanks again

 

Here is the generic prcedure for testing the 5 pin CDI ignition system:

But let's go a bit further on the BRF (big red flag) in the previous post. You measured zero ohms to ground on the Timing/Trigger pin, and you get zero volts for the trigger signal while cranking the starter motor. These are both wrong. This wire should not be shorted to ground. So the next question is whether it is shorted to ground somewhere in the wiring harness, or is it shorted to ground inside the stator (which is where that signal comes from).

Look at the color of the wire in the wiring harness fro the timing trigger pin at the CDI connector. Now go down to the stator area where the stator wires emerge from the engine cover. Follow the pigtail wires up to a connector(s) where they connect into the wiring harness. Find the same color wire noted above in the main harness (this is still the timing trigger wire) and note which wire it connects to in the stator pigtail wires. Unplug the stator from the wiring harness and measure the resistance of that wire to ground looking into the stator. If it is zero ohms here then your stator is bad. If it reads 150 ohms (or so) then we got to look further into the wiring harness. Sometimes quads have a kill switch that shorts the trigger line to ground, or maybe you just have a frayed or pinched wire somewhere. But the first step is to see if the short is in the wiring harness or in the stator...

 

Ok, I am just out of the garage with the test answers.
Method 1, I unplugged the kill switch wire at the CDI and still no spark
Method 2, My scale for Ohms only goes as low as 200k so I probed the kill switch wire and a engine ground resulting in 0.60 ohms.
1. My ohm meter setting goes from 200-2000 so I set it to 2000 and measured the ac ignition power pin and the ground pin resulting in 337 ohms
2. measuring the timing trigger pin to the ground pin my scale did not change.
3. With my meter set to 200 volts AC (low as it goes) I probed the AC ignition power pin and the ground pin while cranking which gave me a reading of 47.2 VAC
4. On a 200 volt AC scale (low as it goes) I probed the timing trigger pin to the ground pin. The result was 0 until I let off the starter button then numbers came up but quickly returned to zero. It dont matter if the kill switch is on or off, plugged in or not.
A. Setting the meter back to 200 ohms I probed the ignition coil pin and the ground pin resulting in 0.5 ohms
B. With the CDI plugged back in I set the meter to 200 VAC (low as it goes), I set the kill switch to run, and back probed the ignition pin and a engine ground resulting in no movement on the scale until I let off the starter button then numbers came up but quickly returning to zero. It dont matter if the kill switch is on or off, plugged in or not.
The last test was your BRF(big red flag). I set my meter to the 200 ohm setting. I traced the timing trigger wire to the engine housing where I probled the wire and a engine ground which resulted in no movement in the meter.
I ran through all of these tests 3 times to make sure I didnt make a mistake and had the same result each time. Hopefully the answers lead to a diagnosis. Thanks again for the help

 

My comments embedded in blue...

If I'm deciphering your data correctly I think we are looking at an open trigger coil in the stator, but the answers above will hopefully clarify that somewhat. There is also an issue with the kill switch pin measurements since you are measuring resistances that are not open. But disconnecting the kill switch wire to the CDI did not cause spark to return, so this is a secondary problem. Let's attack this on two fronts by doing all the measurements and see where this leads.