If it's anything like the other ATV fuel tank "filters" I've seen it's a wire mesh screen, not unlike the "filter" on the feed side of the oil tank headed to the engine. Usually not fine enough to stop all dirt, which is why when you're low on fuel it's possible to pull the sludge and dirt from the bottom of your tank through into the fuel delivery system. Cleaning the tank itself may yield more benefit than cleaning the filter, that and installing an inline paper filter.