Rust is another issue.
Because it's so-problematic, a rusty tank is one of those things which just cannot be overlooked, it certainly
isn't going to 'go-away.' The small particulate material from the rust will constantly clog your carbs' pilot jets, necessitating repeated carb removals and splitting the carbs into two pairs, to be able to access the jet block, to remove the jet block, and to remove/clean the pilot jets, and anywhere-else the rust has lodged. If you are removing the jet block, buy jet block gaskets because these usually will tear when you remove the jet blocks. You need four. #35, here:
https://www.ronayers.com/oemparts/a/yam/50045c0ef8700209bc7942f3/carburetor
The pilot jets (#42) are cheap, and you save having to try to find something small-enough to clean them, the holes are
really-small. I usually use a pin vise and a tiny SS wire about an inch long, with a lot of care. What you need to do, is to scour your tank, and to use one of the coating products on the market. You might find a local jobber by you to do it, maybe a radiator shop. Be aware that the coating products have to be used
exactly as-described, because to try for shortcuts will inevitably result in a botched-job, and will require you to scour-out the tank again, and to repeat everything.
There are plenty of threads on here about how-to scour the inside of the tank, and then seal the tank. POR 15 is one method, Red Kote, is another, another is KREEM, for sealant. Heed the warning above.
Dannymax and Sean Morley will confirm, improperly-using a coating product will just create more problems. I'm sure that if you didn't want to try the procedure, either one of them would be happy to do it for you. Don't be surprised though if upon receipt of your tank, they inform you, "the tank is no-good." I'll tell you what my friend who is a Yamaha dealership mechanic told me: "
don't mess-around with trying to clean and to seal a rusted tank. Bite the bullet, buy a new one. It will save you time and money in the long-run." He's been a Yamaha dealership mechanic since before the VMax Gen 1 was released, he's built hot-rod versions, repaired many 2nd gears, and has cleaned many a VMax carb rack.
I've used vinegar to remove tank rust, just make sure that you remove the tank fuel sender, and replace it with a block-off plate, use the base of the fuel sender unit to accurately drill the bolt holes. Smear it with some Permatex gasket sealer, and bolt it on. Several days, you can drain the vinegar, or whatever rust remover you choose, to see how it's doing. Be aware some more-caustic rust removers may only require a much-shorter timeframe! Evaporust is another popular method.
Adding some metal to the tank with the rust remover, and then agitating the tank repeatedly is another method to break-up the rust. I've read of someone wrapping the tank in heavy carpeting, secured with duct tape, and then inserting the 'ball' into a dryer, and putting it on 'air-dry.' No heat, no liquid in the tank. I've never tried this, and the machine does all the work. Probably a soak session once the dryer method has removed most of the rust, is how to proceed. If you choose this method, take before & after pics, and post 'em.
You can also try electrolysis, there are many articles on the internet about this. Here's one, you can find others on youtube.
https://www.motorcyclezombies.com/rebuild-tune-motorcycle/carbs-fuel-air/remove-rust-gas-tank/
Bottom line, you need to do
something to remove the rust. Many people use some type of sealant, do your internet research, come-up with a plan, and follow it.