1982 750cc Yamaha engine makes poppin noise out the exhaust

I have a 1982 yahamha 750cc with 4 carbs on it, what it does is when you rev it up it pops out the exhuast. Does anyone who has had this problem know the cause and how to repair it?

that would be a backfire, id try cleaning the carb and make sure everything is working right

Also could be the pipes, but probably just the carbs needing to be rejetted.