l probaly want a 125 2 stroke or a 4 stroke 250 but what brand and which one and l want a sport not a trail bike peicer thank for any

if you weigh that much, you will need a much bigger bike (i have never met a 170lb 13 year old) besides 125s are very small, 250s (now were talking)


get a KTM, theyre nice and fast!

or

Suzukis or hondas (theyre fast and very reliable)

dont listen to ltzrider

Suzuki is r terrible especially the 2008 rm-z

like l said on ur other question.

Honda CRF 250R
Kawasaki KX 250F - Monster Energy Edition (Absolute gem to look at)
l would recommend sticking to a four stroke for ur first bike.

HOWEVER. l will expand

the honda will be great bike for u its racing ready
here is a review: http://youtube.com/watch?v=aBJbTiC-5mU
it will require little maintenance & parts r easy to find

the kawasaki has more guts, more torque/speed etc.
plus the monster energy addition is absolutely stunning.
however, it will be a little more time consuming in terms of maintence but the parts will alos be easy to order.

personally, i'd buy the kawai