What dirt bike to get for a beginner? Want small but not uncomfortable for a 6' 180lb rider.?

I would like to get a dirt bike for some trail riding and to just ride around off-road (not street legal). I would like to get something smaller and light but I am 6'1" and 180lb so I don't want it to be too uncomfortable. I am not sure how the bike sizing goes with the motor size. I would like a 125cc or so but that might be too small. Any thoughts. Also any suggestions on models would be great.