I am 13 and i own a 01 Honda XR100 and i am getting ready to sell because i grew to 5´10. and i havn´t had much of a problem except the fuel air ratio was pretty lean. The only other problem that i had with it was that the 1st gear was incredibly low so i bumped the front sproket up a tooth and it made a huge difference. The only trail riding problem is that the suspension is kinda weak, but it has plenty of power but i am just ready for more.