I had a hotrod crank in my lt250r, It done real well, i just replaced it with a oem crank.The rod bearing  on the bottom was getting play. My own fault, didnt run the wrist pin bearing with any thrust washer and it caused to wear out faster. but other then that no problem. I say 90% of the stories of them failing is from in proper break ins.  But i dont know why they wouldnt make them for the 500.