@alexeatscrayons,
												Are you looking to take out a loan?  If you are paying cash, there is no age requirement I know of.  You should probably listen to your mother and hold off until you are 18.  It's not like you could hide the bike even if you purchased it.  
 A note of caution to help you understand your mother:  In my Navy days, I was the safety officer for my boat.  The Navy kept outstanding records on sailors and accidents and one that caught my eye was that 95% of sailors who registered as motorcycle riders on base laid their bikes down within six months.  I have asked riders over the years about this and every one of them has gone down, some multiple times.  My bother went over the hood of a car that didn't see him and ran a stop sign.  A man who worked for me was killed in an accident.  A guy at work had a deer jump in front of him and suffered significant injuries.  You are seventeen and I'm sure you think you'll be different.  Those Navy guys were typically 18 and 19.