I have configured units on bridge mode as per the configs, the tx/rx rate shows between 200/270 Mbps both tx and rx , tx/rx signal about -50/-50 but when i copy a file from the remote site i will hardly get 10 Mbps, can somebody explain why this scenario, distance is 2 Km
May be it's more simple than you think.
First: how do you mean by "copy a file" ? FTP/HTTP download or what else?
Second: try to copy the same file in the same way (i.e. same protocol) on your local wired network. Ideally you should repeat such test on the local networks on both side of the wireless link and between the same system (this is not always possible, I know). Take note of the results and compare them with the values obtained on the wireless link.
May be this is not your case, but I've seen countless people wasting tons of time in trying to "fix" a perfectly working network only to discover the Most Obvious Thing Of The World: the speed bottleneck was NOT in the network (but in the harddisk's transfer rate, or in a cheap network card, a faulty or overloaded switch/router/firewall/computer, etc.)