Yamaha TTR90 Fahrer- Und Wartungshandbuch Seite 8

4. When transporting the machine in
another vehicle, be sure is kept
upright and that the fuel cock is
turned to the "OFF". If it should lean
over, gasoline may leak out of the car-
buretor or fuel tank.
5. Never start your engine or let it run
for any length of time in a closed
area. The exhaust fumes are poison-
ous and may cause loss of con-
sciousness and death within a short
time. Always operate your machine in
an area with adequate ventilation.
6. Always wear a helmet, gloves, boots,
trousers, and jacket for motocross
riding.