error 414 uri too long

hi guys, when i try to post long data without ci, via phpmyadmin for example, it works as it should, but if i try to post the same data via ci ( $this->input->post() ), i get 414 data, is this prevented by ci? how can i solve it?

p.s: i am posting with ajax, n i set the application/x-www-form-urlencoded header