i have a trx 200sx and my wheel bearings keep going out now...i grease the hub real good but i cant pack the bearings because they are sealed...the factory stock bearings on the other side are lasting longer than the new bearings i put on it...do they have to be non-sealed bearings or what could be going on?

 

Front wheels you are talking about correct? Is the brake drum(spindle) nut on tight?, if not the drum will be loose and wobble causing the bearings to wear. When I had my trx200sx I would buy sealed bearings and still pack grease around them.