i raced motocross for 2 years and now i want to ride street and stunting  i'm i really little guy and wut would a good beginers bike be ??  

The best starting point for you would be a 600. they are light, fast, and fun. If you plan to stunt then you will need to do some mild mods depending on what kind of stunts you wanna do. For wheelies you will need to change out the rear gearing. No more than 10 teeth in the rear if you plan to ride on the streets, any bigger and you wont have enough highway speed. also if you change out the front sprocket than it would be 1 down in fron equals to 3 up in the back. Just remember to get something that will fit your style and size, you can lower most 600 if they are too tall. If you will stunt than you will fall, so it wont be wise to buy a new bike, best to go used and cheep untill you are more proficient. Good Luck and always wear you full gear.