sounds like there is too much strain on the starters ?..you may want to check to see if the engine can be turned over easliy by hand..if not..then you got some bearings or something hanging up.
i'll tell you something else it could be too..the one way bearing may be hanging..draging the starter.which..in turn..over heats it ??..just a thought.I fixed a 660 Raptor a while back that wouldn't turn over with a new battery and a good starter and that was what was wrong with it. It would turn over sometimes and sometimes it wouldn't, mostly it wouldn't. The Rubicon is a little smaller engine, so it may turn over, but just put a lot of extra strain on the starter.