I have been working on a 425 with simialar issues. I have checked everything I can think of. Stator ohmed bad,exciter coil was bad also. Bought a new one aftermarket $150 later it had a bad exciter coil. Got a good used stator and put on it. Got it to spark a couple times but it didn't start. I am thinking my problem is the cdi box. I will be working on mine this weekend. I am gonna tear down my running 425 and put parts one at a time from the non-running atv to the running atv. When it don't start I will know what the problem is. I will post on my old thread or this one what I find.
Some older polaris models had a problem with the fuel tank rubbing the spark plug wire and breaking it down causing it to be bad.
I hope you figure it out.
Post your results.
2008 Dodge Caliper
2010 Chevrolet Equinox
2004 Honda ForemanES 400 4x4
(Currently I don't own a Polaris but I work on them all the time and get to ride cutomers for test rides. Maybe soon I will be a Polaris owner.)