Honda CRF50F Owner's Manual page 150

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.
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Technical Information
Oxygenated f uels can damage paint and
plastic. Damage caused by spilled f uel is not
covered under warranty.