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Search the Dirt Rider Forums:Mapleleafmx is our resident Kawasaki expert. Kawasakis are as good as anything else these days.
What kind of riding would you like to do? What is your budget?

Are you leaning towards a two stroke or four stroke? Like Kiwi said, a lot depends on whether you ride track or trails.
A 250f might be a bit tall at 5'5", and I'm not sure a screaming little 2t is the best bike to start off with, but a KX100 is only 100 cc's and you're only 16, so it might work out as long as you're careful.
Have you done any ridding?
What kind of ridding do you want to do?
Do you want to compete?
Are you mechanically inclined?
Are you on a tight budget?
Get the Honda CRF 230.
Get a japanese bike with low hours (preferably Honda) 250 F or 250 2 stroke 2005 or newer. At 220 lbs you will hate a 125 2 stroke. As for transporting it get one of these:
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