ive finally had enough and am going to just buy a new carbuerator, 77 xr75 dirtbike, will i need this thing tuned or should it come that way?

It should come ready to ride. The question will it come tuned to fit you wants or needs. That I guess depends on your wants and needs.

It’ll come tuned close enough for the engine to run, but it’ll surely need tuned to optimize performance for your particular engine.`