A donor bike is a ridiculously small mini-motorcycle that has become a nationwide menace the past few years. Donor bikes are identified by the presence of an idiot behind the handle bars, no helmet and a blatant disregard for traffic rules. Additionally, 80% of riders at some point become organ donors after the required fatal crash.
"Look at Jose on his new donor bike!!! Hope his organ card is updated!"
A used motorcycle bought cheap for the sole purpose of using its engine and/or parts on another motorcycle.
I bought an old GY6 donor bike today. Finally my 50cc engine can swapped!