have a go:
企图做；尝试做
Let's have a go at it.
have a try:
试试看,尝试一下
Let's have a try!
语气上,go更加强调动作本身和对象,比如针对什么人、什么事情；而try更加强调进取,强调主语的能动性.听者的感觉上,激励性的用try.