I recently purchased a 2004 Eton Viper 90cc. This had installed the OEM CDI box with the green wire on the back. But since my daughter is newer to ATVing. I wanted to slow it down a little bit before being used to it. I installed an adjustable CDI box that came on model year 2005. But now I have no spark, all seems to be connected correctly, I switch back to the OEM box and sparks and runs good. This is the second box I’ve gotten since I thought the first was a defect. Is there a different wiring setup or factors, from the OEM CDI to the 1 year newer ADJUSTABLE CDI?

 

Possibly, ETon kill switches generally use an earth to run CDI. My guess is one of those CDIs will be earth to kill, so won't work unless the kill switches are altered. Far easier to turn down how far the throttle lever moves on the handlebars. Before makers started getting too clever, this is how they cut max power, and I your thumb throttle will probably have the tapped hole for a throttle limit screw.

 

OEM CDI is on the right and the adjustable is on the left

all colors are the same, accept the OEM black/white stripe is blue/white stripe on the new CDI

 

Have you wound the limiter to the max? If 0 does mean no spark at zero revs, you won't get a spark at 0.

Black with white stripe is almost universally kill switch on CDIs. Try leaving that blue/white disconnected on new CDI, try with it earthed if you don't then get a spark.

 

I have tried all the dial positions while turning over, no spark. Tried with kill switch in off position. Never tried with disconnected, I will try that.

 

These are the wiring diagrams

 

Right, looks like that wiring set up is, as I suspected, earth to run for the kill switches. If your new CDI is earth to kill, leaving the kill wire disconnected would give a spark. Though trying with ign off would have the same effect, how did you turn starter with ign off? Only other possibility I can think of is a dud new CDI. Has your thumb throttle got a tapped hole for a throttle restrictor screw? Would save all this messing about if you fit one.

 

This is actually my second new CDI box, the first I returned after it had no spark. But after the second one had no spark I suspected another issue. I tried to start with the engine stop ( kill switch) off, ignition on. It has a throttle limit screw, but is already turned in all the way, where it barely moves. But since it is a CVT, still revs up enough to move the belt into a speeder position.