What Slakewell said,if you'ne not in a great hurry then lie the bike down on one side,then every day walk past the bike and give it a decent squirt of crc,penetrine,wd40 or whatever tickles your fancy for a week or two,(the more patient you are the easier it will be), i then use a piece of key steel and mildly tap away with a 4 to 5 pound hammer,if that does'nt work then i use the heat as described above and that's about all it takes,patience is the key,dont just get a bigger hammer and smack as hard as you can or other "cracks" start to appear.
cheers Dale.
P.S. i have also used the thin cutter disc on a DT200 swingarm bolt,it worked but then i still had to get the rest out but yes ,definatley an option.