The petcocks should have screens in the tank and some also have a screen in the petcock outlet. I consider fuel filters mandatory. the little conical ones flow plenty, look good and protect the carbs from all the dust the tank sucks as it goes dry again and again. the stock screens are to coarse for this.

Most owners don't "plan" to put their trusted bike into storage. They have some type of medical or family emergency, which leaves them unable to care for it after a certain calendar date. That means most of them are put away with fuel in the tank. Therefore, there's usually 2 types of trash: particulate and old fuel scum. The particulate could be paint or rust scale from the interior of the tank. The the scum is whatever compound managed to varnish its way onto the system interior while the old fuel slowly evaporated. Both of these are unwanted and need to be dealt with.

► First, pull the petcocks off the tank. There may or may not be screens, but there will be excess debris collecting in the "well" formed by the tank/petcock interface. Blow that off with compressed air.

Before and after

► Then I like to install the small, conical fuel filters which help remove all the particles that would otherwise clog or impede the float valve. Such as these from K&N.

► Finally, the fuel needs to have cleaners that will scrub all the scum out of the system. The best indicator of the condition of your fuel system is the bottom of the float bowl. Whatever you see there is also inside your tank, petcock and fuel lines. What you should be seeing inside that float bowl is clean, bare aluminum. If you feel like you need a cleaner to speed things along, then I suggest a product called StarTron, which is both a stabilizer and cleaner.

Hope this helps.