how tight does the chain have to be?
and how do you tighten it?

 

loosen 2 bolts almost all the way on the side by the disc break... then the 2 bolts on the front u see with nuts on them u loosen the nuts and tighten the bolts at the same time keeping as even as possible because if not it will turn your axle a little bit.. and u can tighten it with about a 1/2 inch of play but the maximum is a unch and a half of play up...