My yz 125 starts first kick but when im ridding it it wont give full power im getting some smoke and some black oil can you help not been into bikes long

You might want to check your air filter first .. mine was doing the same thing ,.. and i checked the air filter and it was covered in oil so it wasnt getting enough air when i tried to take off ,.. if the air filter looks good , you may want to pull your spark plug and look at it ,.. if it is covered in black it is time for a new one .. or a really good cleaning ,.. i found a wire brush and penetrating oil works well ,.. blow it out with compressed air and wipe off all that you can before you stick it back in ,... other than those i hear the rings are only good for about 20 hours (non-racing)
thats where i would check next ,.. let me know if this helps =D