I'm 14 years old turning 15 in early December. I'm really interested in dirt biking and atving and such. Most of my family or friends do or know people who race them. I think I've come to my decision of a dirtbike after reading a small amount about each. I was wondering what kind of dirt bike I should get. I am between 5'5 and 5'7.(haven't checked in awhile.) and I'm around 105-110 pounds. I kinda want to use the dirtbike in the race area once I get very comfortable with it, or just for self entertainment, and maybe some dirt track-like trails. I prefer Kawasaki or Honda. They're from what I've read similar in performance, etc. I have very little experience riding a dirt bike with a clutch. Should I get a 2 or 4 stroke? 125, 150? Lower, higher? Help!

Thanks