Never rode a dirt bike. 16yrs old, 205lbs, 6ft, want a used dirt bike don't know what size of bike to get etc.

DO NOT get a 4 stroke 250 trailbike. Tons of dealerships reccomend them and they are SUPER heavy, not good for jumping, and overall sluggish. Only the racing 4 strokes are good, my brother's got a yz250f and he loves it. It is light, fast, and inspires jumping. Biggest problem is that it is Very loud. The 2 strokes are fast and even lighter, but must be kept in the higher rpm's. The power to weight ratio is much better, but they tend to scare beginners because you must keep the motor Rev'ed up pretty high. The big determining factor is how big you are, and what you feel you can handle. If these seem slightly too big, but you still want Alot of power, they make 2 stroke 100's (a bit rare, but great bikes if you get a young one) and 4 stroke RACING 150's (ex. crf150r). It all depends on what you think you can handle, you can always step up if it is getting to small. Also, if you are riding near a neighborhood, niose is a BIG factor. Cops and pesky neighbors are a pain. If you have ALOT in your area, you may be forced to get a 4 stroke trails bike, as the only good thing about them is that the noise they put out is low. Never buy a brand new bike. You end up loosing alot of money when you resell it. For years I have simply gone from bike to bike by cleaning it up nice, and selling it for a profit. Keep this in mind while buying. Major dealearships tend to rip you off. They often tell you that you need a bike that happens to be the Most expensive Bike that they need to get rid of, and they cant wait for a sucker to come by. The only ones you can really trust are small local shops.

ktm 525 exc it is b.a. perfect for a bigger person tons of power!

Anything between the size of 125 & 250 Go to some shops and sit on the bikes to see what fits. Then purchase a used bike.

Since you are a beginner I'd advise against getting something too big too soon. Of course, once you get better you'll need a fairly powerful bike due to your weight, but go easy at first. I would recommed a Honda CRF250X. It's a trail bike with and electric start so that you don't beat yourself kick starting it all the time - remember you're a beginner and apt to stall the bike often as you get used to the clutch. The 250 will move you along just fine and after about a year of riding you can decide if you need to move up to a 450. One other thing, get yourself some good protective gear and a good helmet. Remember, a five dollar helmet is good for a five dollar head! Good luck!