Go to youtube and search. This isnt a model specific problem, so theres plenty of help outthere from other riders and drivers.
Some of the options:
Helicoil
Timesert
Oversized drainplugs
Whatever you do, make sure to use a new washer, and just snug the bolt up. Theres no load on it, and it just needs to hold itself, and slightly crush the washer to seal. My Xt600 is at 177.000km with over 40 oilchanges, without stripped oil drain/filter-bolts