No a motorcycle uses power from the battery in normal everyday use as it requires a stable source of power .. The charging system replenishes the power in the battery If you used all electrical items at once on a motorcycle ie full beams , hazards, brake lights illuminated ,heated grips , ABS system activating , Horn ...The alternator would struggle to provide a stable source for the Ignition and fuel injection sysyems . Even without doing the above if you started the bike and isolated the battery from the system yes the bike would run but as soon as you push the limits the FI and Ign will start to struggle .