I have an R27 whose tank appears to be rather clean (red coating intact). The bike has not been started in 20 years and does not have gasoline in the tank.
Can I use rubbing alcohol to remove potential contaminants?
I have some info saved from another forum. It was recommended to use something like keorsene or paint thinner as a solvent. To some degree, even gasoline could be used. Keep the petcock closed and swish the stuff around. Then follow up with common dishwashing detergent and rinse very well. That should clean out the tank pretty well.
Kurt in S.A.