eton viper jr. 40 won't fire
 

My 4 year old son has an Eton Viper Jr. 40 with electric start and I can't figure out why the plug won't fire. I have put 3 new spark plugs in it and the coil reads .4 ohms. Can someone please help so my little fellow will be happy again.

Looking at the published eton wiring diagram your CDI has four wires going to it. Does this match your quad?

If so, turn on the ignition switch and set all kill switches into the "run" position. Measure the DC voltage on the red/black wire at the CDI. What do you measure? It should be 12 volts DC.

Switch over to measuring AC volts on the lowest AC voltage scale you have (hopefully like 2 volts AC full scale). Measure the AC voltage on the white/black wire at the CDI while cranking the engine. What do you measure? It should be a low voltage like 0.2 to 0.4 volts, but it should not be zero volts.

eton viper jr. 40 won't fire
 

Hey Lynn,
Thanks for your reply.
The DC volts at the red/black wire is 12.23
The AC volts at the white/black wire is 0.7

What do you suggest?
Thanks,
Alan

Both those values are good.

Let's review so far:

The very high voltage spark is generated by the coil, whcih gets its drive from the CDI. The CDI needs to be powered, and it needs a trigger to tell it when to fire the spark plug (through the coil). You have power to the CDI, and you have a trigger voltage.

Most CDIs also have a kill pin that kills spark, but your 4 pin CDI does not have this function so we can ignore kill connections. Your quad kills spark by removing 12 volt power to the CDI (interrupted at the ignition switch, tether lanyard switch, or handlebar stop switch), or by removing the trigger signal through the remote module.

You have measured power at the CDI, and a trigger signal. So now you are down to the coil or the CDI.

These can't be measured with a meter very well. 0.4 ohms on the primary sounds about right (I've no specific experience with etons). You could measure and make sure the secondary winding has continuity. Else you are down to guessing.