vCard Export - Japanese /Chinese / Korea Character

Please help me to figure out the vCard export from contact , I got the vCard with question mark on asian character. I also try to modify the /core/class/vcard.cleass.php line 101
from
public $encoding = “ISO-8859-1;ENCODING=QUOTED-PRINTABLE”;
to
public $encoding = “UTF-8”;

It dose not work, Is there any way to get this done.