you need to take the three bolts out the front wheel,then undo the brake caliper and take it off ahen undo the nut in the middle of the hub and pull the hub off the spindle this may need some force so you may need a rubber hammer to do that then you will see a abearing on each side of the hub you need to put a drift like an old spindle in there and knock the centre spacer over one way then get the drift on the edge of the bearing and then knok it out and then the same of the other one.when you fit the new new ones make sure you drift them in usinga a suitable sized bit of metal or socket that fits the outer edge of the bearing not the inner one or you will wreck it.
adam bike doctor(of milton keynes motorcycle centre), February 2011