In this post, I will explain you how can we change the default port of SharePoint. 
To do that, take the following steps.

1. Goto IIS, Right Click on Sharepoint Site and change the port (Lets say to 90)
2. Goto Sharepoint Central Administration, Click on the operation tab then Alternate acccess mapping under global settings.
3. Now you can see the list of sharepoint sites. Now edit the one without port, and alter the URL. in My case I change it from
   http://srv-production to http://srv-production:91

And you are done with port stuff.