Has it been ran in a while? Clutch plates could be sticking...put the bike in 3rd or higher gear and roll the bike back and forth with the clutch disengaged. Make sure the wheel spins and doesn't slide when doing this (it's okay if it slides but means it hasn't broken them loose yet).
Otherwise, you need the battery charged up.
Or, take a look at these steps...https://tw200forum.com/index.php?/top...dpost__p__6960