How do you tell if the stator is bad? Other than the battery not charging.

 

I don't mend Polaris bikes so this info is generic. If a bike isn't charging, suspect voltage regulator first. Check the voltage across battery with engine running, shouldn't go much over 14.5v but should alter with revs and be more than when engine is switched off. If it isn't, check if regulator is warm, this indicates the alternator is putting some power into regulator, but is not conclusive. We would fit a new regulator at this point. If it then charges, problem solved, but if you wish to do the tests before spending money, disconnect plug from regulator, two or three wires come from battery to it, one negative and one or two positive. Put a high wattage 12v test lamp across these terminals, lamp should light brightly, if there are two pos, one will be live with ignition on, 'tother live all the time. Three wires come from stator to regulator plug on most big Quads, check with an ohm meter between each two wires in turn, all resistances will be low but should be the same, within a few ohms. Then check resistance between one wire and earth, should be open circuit. If these tests don't show problems with stator, a new regulator should fix it, but if a new regulator doesn't, then you will have to fit a new stator. I have known stators to test OK but not work, however did look "deep fried" when removed.