I suggest that you and your girlfriend consult with a business attorney to memorialize the agreement that you two have with the motorcyle with respect to loan she was able to get for you and your obligation on paying it down. Included in the agreement would be terms that you are obligated on the loan that she received and her transfer of title of the motorcyle to you when the loan is paid off.The document needs to be approved by both of you as well as dated and signed.