There is no su binary installed on my ZTE Z 730. How do I fix it?

[twistidme]

there is no su binary installed on my zte z 730. how do I fix it? HELP!

I need to install a custom recoverybut I cant because I'm not rooted, and I can't get root until I fix my binary. Somebody please help me! ZTE --z730 4.3 jelly bean