Fuel will have no effect on engine temperature. See if your fan works. One test is to unplug the wire from the radiator temperature sensor and short out the two contacts on the end of the wire. If the fan comes on, at least you'll know it works. The sensor may be bad, the radiator not full, the thermostat stuck or the radiator fins clogged though. Check the radiator to make sure it is full and and that you can see a light through all its fins. If the fan works, let the bike run to make sure the fan comes on before the fourth bar appears.