Yamaha DT501988 Owner's Manual page 14

4. When transporting the motorcycle in another vehicle, be sure it is kept upright
and that the fuel cock(s) is turned to "ON" or "RES" (for vacuum type)/"OFF"
(for manual type). If it should lean over, gasoline may leak out of the car-
buretor or fuel tank.
5. If you should swallow any gasoline, inhale a lot of gasoline vapor, or allow
gasoline to get in your eye(s), see your doctor immediately. If any gasoline
spills on your skin or clothing, immediately wash with soap and water and
change your clothes.