Has new spark plug has spark, fuel and turns over but will not fire. Tried starting fluid just backfires

 

How many miles are on it? Sounds like it may need a valve adjustment.

 

Just did a lot of work on my 02 Sportsman 500 because of warm engine shutdown. Turned out to be a $4 spark plug which surprised me as I just knew it was something more exotic. New cdi, battery, fuse link, rebuilt carb., and coil. With regard to your problem of no start, if it's backfiring your getting spark albeit intermittent. Double check the plug. A crack will cause this. Double check coil wire connections and pick up coil. All were suggestions from not only Polaris and "Old Polaris Tech". To his family, my condolences. He sure seemed like a good man willing to help others lost in the ATV repair world.

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02 Sportsman 500
17 Sportsman 1000xp