Honda TRX500FA Owner's M Operation And Instruction Manualanual page 276

Oxygenated Fuels
If you notice any undesirable operating symptoms, try another service
station or switch to another brand of gasoline.
Fuel system damage or performance problems resulting from the use of
an oxygenated fuel containing more than the percentages of oxygenates
mentioned above are not covered under warranty.
Oxygenated fuels can damage paint and plastic. Be careful not to spill
fuel when filling the fuel tank. Wipe up any spills immediately.
Oxygenated f uels can damage paint and plastic. Damage caused by
spilled f uel is not covered by warranty.
Technical Information 267