Get the quaud bike early in the game
Ok what you have to do is go to the map and look for the stadium then look to the right and there will be squiggles marking a motorbike track. once you get there find the quadbike and then look for a dirt bike and it will have a mission.get halfway through the mission and drive over to the quad bike and hop onto it. drive the quadbike until it says"you have failed you have left the track".then you will have to exit the mission and find the quadbike that you parked somewhere else not the one on the track.when you find the quadbike you could save it in your garage if u r out of the army base or you could just drive it around. cheers - if you have any problems finding the track e-mail me and ill send u a picture back and to let me know that you need help is just make the subject"mx track gta:vcs" thanks cheers!