I have a Zunddapp 125 MX that has DID magnesium rims on it. I can't remember if these were banned by AMA because they tended to self destruct. Any better memories out there than mine on these.
.............no ban I am aware of,you may want to consider keeping them "sealed" from the elements via a good clearcoat to prevent them from secumbing to oxidation,if the metel has a fine white powder on the process has begun..............