Each state has its own statute of limitations which restricts the length of time that may pass between the date of injury and the date by which your case must be filed. In some states, that statute is one year from the date of injury; in other states, it can be two or more years.
You must educate yourself as to the requirements in your own state. The simplest way to do that is to contact an attorney who handles motorcycle personal injury cases in the state where you live.
A general exception to a statute of limitations is when a minor was injured in an accident. In that situation, minors generally have until their 18th birthday, plus the statutory limit to file suit. So, the statute is "tolled", or put on hold until the minor is 18. For example, in California, the statutory limit is two years to file a personal injury lawsuit. Therefore, a 14-year old would have two years from the date on which he turns 18 to file suit, or six years total.