I'm sorry about that, I have a 16 year old turning 17 that lives 2000 Km's away.
I don't get to see him much anymore either.
I would like to help you, what do you have so far?
I have a 'spare' motor (in bits) which I was keeping for my Drift Trike Build, that I'm thinking to replace with a new motor, but to send to America? Australia Post is ridiculous. And the motor ain't that flash.
You might be better off saving for a car at your age? But that depends on how urban you live. I live in the country, and a car is essential for me.
But my advice would be not to blow to much money on a motorized bicycle at your age.
Keep it simple for you first build.
Get your self an Ebay kit, and do some research, ask us questions if you have trouble, Inspect the motor properly before you run it and give internals a clean out,
Run it in before you do to many mods,
Then do one mod at a time.
Getting your compression ratio correct would be my first suggestion.
But don't over do it either, as your motor won't last long if you give it to much.
Open the exhaust a little, with out drawing to much attention to your self.
And get a 39 t or 41 t sprocket if you feel you need a little more speed out of her once you got her running right.