Motorcycle Title Transfer with a Bill of Sale Only

The DMV is correct. Unfortunately, this transfer can not happen; mainly because there is a missing out of state title involved. You must have the motorcycle's original title to transfer it to your name. Assuming the title is lost, the only option you have (which still requires you get in touch with the original owner) is to have the original owner transfer the motorcycle to his or her name in California (this is allowed as long as they have a registration card from out of state or if they apply for a duplicate title in the state which it was registered in last), and then after receiving a new California Certificate of Title, transfer the title over to you as a normal change of ownership. So this process will take... you getting in touch with the seller, asking the seller to obtain California registration and then legally transferring the motorcycle to you. Depending on the value of the motorcycle, this may or may not be worth doing. If you can find the seller, and communicate with them through mail or visits, it's possible to get this accomplished. They may assign you power of attorney to complete many of the DMV tasks required in California and out of state.