CB1100RS fuel tank rust

[TheLegend]

Hi everyone,

I recently bought a very well kept CB1100RS, but I noticed something unusual. There’s quite a lot of rust inside the fuel tank, especially around the top section and near what I believe is the breather hole/vent.

What I find strange is that the bike is absolutely pristine on the outside, yet the rust is concentrated only in this specific area.

My questions are:
How serious is this issue?
Is it something that can be repaired, or should I be thinking about replacing the tank altogether?

I’d really appreciate any advice or experiences you can share. Thanks in advance!

Use Hammerite Kurust, I use it with succes on any kind of rust, for over ~ 30 yrs
https://www.amazon.com/Hammerite-5092820...4UMUA?th=1
PS: I wonder why in all adverts, Honda says that at RS/EX the tank is all aluminium?