How to fix biker gang issue in my neighborhood.?

Over 30 of them or more get together few times a week in my neighborhood. They drive Harley Davidson bikes with illegal exhaust that rattles the houses few block away. They sometimes drive over 50 miles or more on 20 mph road. There bikes are so loud and they keep making loud noises all day and all night long and i haven't seen any single cop come to them and arrest them. They piss everybody in the neighborhood and nothing happens. Why isn't police doing anything. Speeding on the 20 mph road is illegal and having loud illegal exhaust is illegal but this stupid people just keep doing it and doing it. Can this problem can be fixed or our county is doomed and police are useless.