No spark on 110cc mini atv
 

I have no spark and can NOT figure it out. I have checked and replaced everything. I have replaced the CDI and the ignition coil and spark plug. I checked and made sure I was getting voltage out of the stator, but still no spark. It just keeps turning over. I keep thinking it is a safety switch of a bad ground, but I have traced EVERYTHING and can not see any problems. Checked all connections and they also look good.
PLEASE HELP with any ideas .... I have to be missing something.

The kill switches on these are hatefull little prickish things. Its not enough to have it centered. It needs to be pushed in as well. Even then it is hard to detect any change..but it does make contact.....waynec

Which ones in particular should I be paying attention too? Is there any one that is worse than the other?

Not sure which brand you have here, but I guess it doesn't make much difference.

Please pay very careful attention to the wiring harnesses and white connector plugs. It is very easy for spade type connectors to slide out of them some and not make contact.

I would also trace your wiring to make sure it's in the correct place. I've seen some of them come with the wires in the wrong spot inside the connector. It's a bastard of a job to find this problem, but a very simple fix.

I would highly doubt any of the parts you replaced would be the issue, and would bet you $10 it's a stupid wire in the wrong spot, or pulled out some.

As waynec mentioned, the rubber plug dead man switch located on the back of them can be a problem as well. You need to ensure the boot is on correctly if it's slightly ajar you won't get spark.

I am assuming you're squeezing the brake if it's turning over.

Correct brake is set. I have traced EVERYTHING and cannot get spark. I even replaced the tether kill switch in the back with a brand new one. Still no spark. I am lost .... Any other suggestions on what to look for would be great!

Does kind of sound like the safety switch... With your brake set, does your brake light come on?

Brake light does come on. Correct me if I am wrong but the only saftey switches that will cause no spark is the rear tether and the key ignition switch and the handlebar kill switch.
The brake lever has nothing to do with spark. It is only to be pulled in order to get it to turn over.
What else would cause no spark ... I have been trying to track this down for 2 days. Again ... I have traced and untaped and uncovered every wire and checked every connection. I can not figure this out. Again, I have also replaced the CDI, iginition coil, tether safety switch, ignition switch, and spark plug. Still NO SPARK .....

This will sound stupid and is not meant to annoy you, but is the spark plug boot making good contact on the spark plug wire? On my sons Mini Beast, the wire pulled out of the connector that goes onto the plug. I remember on my old japanese bikes some of them kind of threaded on but on the Gio it just seemed to push on.

Again, I am sure you checked that already but just wanted to throw it out there. There is an electrical guru that frequents the forums named LynnEdwards (spelling could be wrong) that could probably help but I haven't seen him on for a while.

Sounds like you have covered pretty well all the bases on it. Electrical problems can be major gremlins to track... Very frustrating. I wish you the best of luck with it and am sure you will track it down.

What brand is it?

Has it ever run or is this a new quad for you?

Have you ground the plug on a headbolt to see if there is actually no spark?

Have you replaced the spark plug with a new one? If so, what brand?

What kind of kill switch is it on the handlebar? Is it a two position switch(click on and off) or is it a slider style like on a motorcycle turn signal switch?

Sorry for the rapid fire questions, but it helps narrow down the solution gathering.

- It is a used quad not new
- it is the on/off toggle switch on the handle bar
- Yes, plug is making good contact on the boot. As mentioned earlier it is a new coil with a new wire going to the plug
- Yes, I have tried grounding to the head to see if I can see spark ... even held it in my hand while touching a ground to see if I could even feel the slightest tingle and nothing.
- Tested with a meter and I am getting current from the stator to the CDI, but I am getting nothing coming out of the CDI to the ignition coil. It has to be shorting or grounding prior to the CDI I just can not find it....
- It can only be a couple of wires, but I have checked the logical ones ... tether kill switch, handlebar switch, and ignition switch.

Is this a picture of your CDI?

http://i397.photobucket.com/albums/p...o/50cc-cdi.jpg

If so, set up your quad to run - all kill switches off, tether plug in place, ignition switch on. Then unplug the CDI and use you meter to measure the kill switch pin resistance (in ohms) in the wiring harness to ground. It should read infinite ohms (open circuit). If it reads a very low value of resistance (less than 100 ohms) then you have a kill switch problem. We can go from there.

If you have a different CDI such as a 4 pin version (much less common than the above 5 pin version) then that's a complete different path.

If you don't have a kill switch problem then the next step is to use your meter to measure the power supply voltage to the CDI, the trigger voltage to the CDI, and the resistance of the coil primary to ground. We can go there if necessary.

Kill switch issues (and associated wiring) are the most common causes of no spark and the easiest to fix. That's the place to start. We can branch out from there as needed.

OK here is the update. My CDI does look like the picture. I tested the kill switch pin and it reads infinite ohms as it should. It is not a kill switch problem. The power supply to the CDI from the stator is only reading between 60 - 65 volts AC. I am getting absolutely zero volts coming out of the CDI to the coil. The timing trigger pin measures .2 volts.
Is the stator not producing enough volts to trigger the CDI?

60 volts AC on the ignition power pin is fine.

0.2 volts AC on the trigger wire is on the low side. It really depends on your meter. Since you didn't report something like 0.23 volts AC I'm assuming that your least significant digit on the meter is 0.1 volts on the AC ranges. So it really could be more like 0.1 volts (or 0.3 volts).

The trigger voltage is actually very complicated. It really consists of two closely spaced +/- pulses about 5 volts high (at cranking speeds) followed by long periods of zero volts in between. Volt meters aren't really designed to measure this kind of complex waveform, so there is some variation between meters. Using a meter to measure this is not optimum, but often the only option.

As another data point try measuring the resistance of this pin in the wiring harness to ground (CDI unplugged). You should get around 150 ohms.

Just for informational purposes this is a graphic display of what the voltage should be on that pin:

http://i397.photobucket.com/albums/p...photo/1jpg.jpg

The relatively long periods of zero volts between pulse pairs is why you read much less than the 5 volt peaks.

The trigger pickup coil is outside the flywheel, but under the engine cover. On some quads the gap between the pickup coil and the flywheel is adjustable. You might want to see if yours is adjustable, and then try narrowing the gap. That will increase your trigger voltage substantially. I have read posts from others who have solved their no spark problem by narrowing this gap.

Also make sure that the connection from the CDI output through the ignition coil primary is OK. Measure the resistance from the Ignition Coil pin in the wiring harness to ground. You should get around 1-2 ohms. You should not get zero ohms.

Thanks for the help ... I will try this afternoon and let you know!

Back to the kill switch. I had a similar problem recently. I wound up taking the handlebar kill switch apart & found a bunch of crud in there. Cleaned it up & she fires up just fine now.

Good luck.

John