according to http://www.networksorcery.com/enp/protocol/ip/ports00000.htm the standard https port is 443.
To test what port this is on your site put up a page with this code:
<?php
echo $_SERVER['SERVER_PORT'];
?>
Then go to it with your browser using the https designation. After you've completed that fill in the port that reports to you as $https_port in this code.
<?php
function check_https($https_port = 443) {
if($_SERVER['SERVER_PORT'] == $https_port) {
return TRUE;
} else {
return FALSE;
} //end if
} //end check_https
?>
Then in your pages call this function. If it returns false redirect them to the same page with the https designation.