How do you bar spin on a BMX bike?

Bmx. 350$ bike. handle bar question?

• i bought a bike from danscomp.com a kink gap 2011, my friend and i put it together, but i have a feeling he has know idea what he did. like today i was bunny hopping gaps and practiceing, and like my handle bars move back when i land. and when i tryed to tighten my handle bars they like stripped all 4 stem screws. and now my handle bars are messed up. you cant like feel it. but i know they're moveing back. and i can move them back forward but im scared. how can i fix this problem? i dont wanna spend 100$ for a bike tune up.... just for screws and handle bars. please help.

• Answer:

  If they're really stripped you just need a new stem. $15-$60 depending on the stem. Remove and grease the bolts next time before you tighten them, and you need to tighten them evenly. (as in, not one all the way before the others.)