Should owners of motorcycles register for organ donation?

Everyone should! Aren't you really asking whether motorcycles are so dangerous that the consideration of end of life issues is appropriate? Truthfully, we should all think about the unpleasant topic of our own death, and what we prefer to happen with our own body. Motorcycle owners and all others can best celebrate their own lives by saving the lives of others through organ/tissue donation.
No. There is no compelling reason why any particular activity should prompt registration for organ donation.