Hey there, I just bought a 87 virago its very loud and backfires even when idling how can I fix this and what would cause it thanks gare

I would start with a good tune up, timing?

Definitely sounds like a timing problem.

The carbs need to be the same in air and fuel so get them set. And a good tune up wouldn't hurt if you haven't already done so...

Don't think I would feed equal Air and fuel.
Any mixture less than 14.7 to 1 is considered to be a rich mixture, any more than 14.7 to 1 is a lean mixture.