To increase this size limit you have to make some changes in either the web.config file for the application or in the machine.config file of the machine if you want to apply to all applications that are on the server.

Add this line under the <system.web> tag

<system.web>
  <httpRuntime  maxRequestLength="1000000" executionTimeout="420"/>
</system.web>


Now you get one gigabyte file upload. By the way the default size is 4000kb