I recently faced a problem in one of my WCF projects with HTTPS data packet size, you can change the data packet size only for HTTP binding in WCF but not for HTTPS binding, if you want to know how to do change HTTP binding click here. To send large data on HTTPS you just have to add the following line in your HTTP binding tag then that setting will work for HTTPS too.
<security mode="Transport">
Just an FYI after adding this line in your webconfig file you are forcing user to use HTTPS now for that specific binding.