Assuming you are referring to the red black wire from stator to CDI 37v is fine, but you firstly wrote 0.7v from pulse coil which seems low. As you are adding to this thread, I assume you have checked the air gap on the pulse coil, as stated above, I don't know what the output to coil from the CDI should be, often it is as high as 100v but 20v may be OK, in which case I would stick your original coil back on and see if that fixes the problem.

 

Hi merryman,
thank you for your reply. i have two photos of the stator and the pickup coil for my ATV. The pickup coil shown is fixed by the two screws and has no adjustment i can make. On other ATV's, i seen the pickup coil mounted on the ATV frame instead of the casing. for this ATV model it seems i am unable to adjust the pickup coil for a higher output.

 

You are not supposed to be able to alter the air gap but, as the earlier posts (see post 37) indicate, some have done it. I would at least check the air gap with feeler gauges and compare it to the above.

 

Apologies for the above post, realized later that you can't check the air gap once the stator is on the engine as you can't get at it. Makes you wonder how the previous posters did it, if they were on about Tao Taos. If the trigger on your old stator is OK, it may be worth fitting it back on. This will involve a bit of soldering.

 

Hi,
I was lucky to find this forum and also this thread that has helped a lot with my ATV issue.

We got this Trapper Hummer 125cc ATV which is basically a re-branded Tao Tao Motor Raptor 125cc (ATA-125K), and last friday it suddenly stopped giving spark. Firts we were driving in our yard, pretty much normal driving that we usually do, some uphill/downhill driving in the gravel.
Decided to have a little break, so stopped the ATV by turning the key to off, like we always do.
We had about 2 hours break, then tried to start the ATV like always: Breaks switches on, turn the key, and hit the start button. Starter worked, it tried to start the engine but nope. After several tries, checked the break switches, and kill switches, but nope. Engine wont start.
Ok, I figured out that let's check the sparkplug. Cap off, plug off, then tried to start by keeping the plug next to engine. No spark, ah, so that's our issue.
Battery was running really empty at this point, so I decided to give it a full charge over night and then, saturday morning would continue to check what is causing this.
So, sat morning I started to figure out what is going on. With full battery, I checked the plug again. Starter worked like a charm, but no spark.
Then I followed the plug wiring, and started to check if the coil is dead. Measuring connectivity throug the coil to plug, everything was fine, no issues with connectivity. I measured the resistance in primary and sec in coil, both giving same values that are already mentioned in this thread. So I figured that it must be something with the CDI(AC CDI, 5 wires, signal, ground, power to coil, kill switch, high voltage from stator) or the stator (2 wires yellow to regulator, ground, signal and high voltage to cdi).
With instructions (which are amazing, Thanks for those) written in this thread, I noticed that red-black wire coming from stator to CDI is not giving any ac volts at all. I got the signal (blue-white), or at least it shows 1-5 volts during start so I think that it is ok.
Well, as this ATV has still warranty, I have not opened the stator cover yet as I am not sure if that cancels the warranty, but I am pretty sure that the reason for no spark is the missing high voltage from stator.

I have already contacted the atv service company about this issue, let's see if this is something that I'll do by myself they providing the parts, or do I need to take the atv to service company.
But my question is that what could cause this kind of issue out of the blue? First you have proper spark, then you stop the atv, have a little break the then, boom, no spark. I was wondering, that could the heat or temperature be the issue? Like when you drive and motor is running, engine is hot, stator is also "hot". Then you stop, engine gets cooler as well as the stator. And then that causes this? Like I wrote, I have not opened the stator cover so I can not tell yet what it looks like inside, but in general, this kind of stuff is really weird to me. I have 20+ years experience with these (dirt bikes, atvs, street bikes) but have not encountered this before (well couple italy-made bikes have had ign coil issue out of nowhere :-) ) This is our first china made atv, so could it be just that the quality is just poor in some units?

 

I've had several stators go bad. Most look fine physically. Had a couple break a wire, so it was easy to diagnose. Also had a mounting screw back out and destroyed the entire stator. You never know what to expect.

 

Yeah, true,
This is still a bit mystery, as now I have taken the cover off and got to look the actual stator. There seems to be no physical damage, no loose wiring or anything.
I expect that resistance between Red-Black (Exiter Coil) to Green should be around 400 Ohms, but I get nothing, meter gets nothing on any Ohms scale. Between 2 Yellow wires and directly from stator, I get around 1 - 0.9 Ohms.
Blue-White to Green/Ground is 136 Ohms.

 

It seems that the exciter coil has had it. Worth checking that it isn't the red/black wire broken, by testing the wire at the soldered joint where the wire goes into the black coil, but it looks like you need a new stator.

 

Yep,
Now that I took the stator off from the cover, found out why it failed. I did measure soldering points and noticed that the other end of the exciter coil joints was the issue. There is some silicone-based stuff that should protect the wiring coming from the coil to the joint, but after carefully taking the silicone off, noticed that the wiring is cut. This silicone stuff should protect the thin wire but seem that it is not doing it, as it was not properly attached to the plastic covering next to the coil. So, my diagnosis is that shaking when you drive, etc is slowly cutting the wire as loose silicon is not protecting it.
I sent pics about this to my atv supplier and they agreed to send me a new stator, based on warranty. I also went to a local hw store to get proper silicone which is suitable for this kind of environment. When I get the new stator, I 'll replace the silicone or just add it so that wiring is not getting loose anymore.
I also took my soldering equipment from the shelf and started to figure out if it would be possible to fix this on by re-soldering it back to joint but let's see if it works out :-)