New battery but bike won't stay running 1993 Honda Shadow Will run when hooked up to jumper cables but dies as soon as it is taken off?

First, make sure the battery is fully charged. Even if it is new, check it with a volt meter to make sure it has at least 12.5 or better volts. If not then charge the battery at 2 amp'2. till fully charged. Then try with fully charged battery. Does the engine start? If so, check the charging system on the bike while it is running, without the boost. You have to have at least 13.5 to 14.5 Volts. If not,and you get only the base volts of the battery say 12.5 or less most likely the Stator is defective and will have to be replaced, or possible the regulator. Hope this helps.Good luck