I'm currently in the process of cleaning my Vitesse fuel tank out with white vinegar, (a tip given to me by a local classic bike restorer). So, I left the tank in the shed standing on a bund overnight in the upright position (as in it's fitted position), with 4.5 litres of white vinegar in it. This morning I observed the effect, it has removed all the fuel residue that was submerged below the fluid level and eaten into some rust patches. I have now put the tank on one side to process that are next. I will need to get some more white vinegar to submerge the centre baffle . But B&M are out of stock just now and my ebay order has gone missing.