gas tank cleaning...

I will jump on this as my son's 67 notchie gas tank was darn right gross on the inside.

I put a big chain inside the tank and shook it around for a while. That knocks out the big stuff.

Hydrochloric acid (commonly know as muriatic acid) will take care of the rust.

Acetone will take care of the sludge and gasoline varnish.

Came out really clean. Rinse it out with water and let it air dry. Good to go.