Found black flakes in my gas tank. Hmmm...

It was a new old stock tank. Was never used before me. Inside was clean as a whistle (exactly what you'd expect from a brand new tank). I rinsed it anyway with gasoline before using it. But there are black flakes in it. One is kinda big. The other ones are the size of pin heads. But one of them is the size of a dime.
What is the best method of rinsing a tank and actually getting the garbage out (and not just caught under the fuel cap area)?

 

IMO, Siphon.

I had a tank that was severely peeling from some botched tank coating job by the PO. There was crap floating in it and I couldn't seem to shake/rinse it all out for the life of me. I found that filling it about 1/3 of the way and shaking it up, then letting the crap settle, I was much more successful siphoning out the crap sitting on the bottom than trying to shake it out. After a couple passes I pretty much had it all.

 

shop vac

***EDIT*** but not if it has any traces of gasoline in it; you don't want the vacuum motor igniting fumes.

 

It was the gas I was using. I pulled the petcock and the screen (which was brand new before I started riding for this season) was coated solid with deposites. Some of those deposites which sorta hardened had flaked off into the tank. I was using this gas from an old station out in the country labled "Real Gas". It was 93 octane with NO additives or ethynol. But it is very dirty. Decided to pull that when I inspected the filter and actually saw debris in it.
I cleaned the inside of the tank but havn't coated it as it is really clean inside. Pulled the carbs and cleaned them. They were still pretty clean but I gave it to my dad and wanted him to have a fairly fresh start with it.