I'm not sure what your options are, or where you should start, beacuse you haven't provided enough info. First of all though, any bike that is given to you, or any bike that you have at all is a good one. '98 isn't THAT old, and I can't imagine it being too crappy. You say you need to rebuild it? My advice would be to purchase a manual for the bike and start the teardown to see what condition the motor is in. Get the head and cylinder off, and check the condition of these parts, replace the piston, rings, etc, and get a rebore if nessecary. Check out the bottom end as well. More information would definitly help everyone help you get it up and running! Let us know!