I've said it a few times before in other threads, but ill say it again here. USB endoscopes are awesome for inspecting inside gas tanks, cylinders, pipes, your colon, etc.
One thing I cannot stand is crud and sediment in my gas tanks. People say to just use inline filters, but i have never found a filter that kept fine sediment out of my carb. It always settles into the bowl, and eventually gets sucked up by your jets and can cause scoring, or just clog things. I sold a spree to a guy, and it was brought back to me twice having died on him. For some reason the bike was SUPER sensitive to any junk in the fuel, even a tiny amount of super fine sediment would make it stall out, filter be damned. Got myself a new endoscope with USB C so I could check the tank out and found that although it looked pristine after multiple cleanings, it still had tiny amounts of stuff in it. The spree tank has some crazy baffling in the roof of the tank that kept creeping out with vibrations. Finally got it clean, hasn't had a problem since.
You never know what's lurking in there. Even if your gas is coming out clean ish, many petcock bungs are not at the lowest point of the tank, so the tank becomes a sediment trap that slowly lets stuff out over time.
The camera is really helpful in that it lets you know what you're up against, and how far you need to go.
Heres a pic I just took of the inside of my Cimatti 86 tube frame tank. There was a couple spoonfuls of rusty jank that would turn my gas a dark brown. The bung made a lip inside about 1/4 in tall, and the last of the stuff wouldn't come out. I attached a length of 1/2in fuel line to my shop vac, put some water in the tank, and vacuumed out all that shit. Confirmed with the camera that all was good afterwards.
Possibly the dirtiest tank of all belonged to my euro sped ciao mix. Pic was taken after hours and hours of rinsing with a hose, pressure washer, hot water, degreaser etc. Repeated my vacuum trick, worked great. I taped the hose to a coat hanger, and the camera too. To help guide it through the bracing/baffling.
They're like $20 and a sweet tool to have. Usually have embedded lights, and attachments like hooks and magnets for retrieving stuff. Thanks for coming to my TED talk. (edited)