how to convince my parents to let me get a motorcycle?

my mom has motorcycle phobia. she has no reason to give me but"they are just so stupid". she let me get a moped and i have been riding that for about 1/2 a year but 2 days ago the motor stoped working so i cant ride it anymore. she is deathly afraid of letting me ride anything over 50cc, she thinks that because its called a motorcycle im going to go kill myself instantly. i think i can move up to a 250 but she thinks because its 5x as big it will go 5x as fast, my moped already went 60mph. how do i get my mom to let me get a motorcycle? i work(alot), very responsible(always have A's in school), and safe(i never get hurt because i use all safety percautions). i want somthing thats my own and i cant afford a car because i cant finance, i dont want to buy on the edge of a cars life(had a bad experince when i bought my moped with10,000 miles on it). i cant prove my responsibilty to her if she wont let me make my own decisions(like getting a motorcycle) she thinks 16yr old+motorcycle= dead