Cleaning and Sealing the Motorcycle Gas Tank

The gas tank on this bike was pretty disgusting.  All the exposed metal inside the tank was rusted and the bottom was caked with some crusty gunk.  My plan for the inside of the tank was to get as much of that crud out of there and then seal it with a permanent liner.

The first thing I did was rinsed it out a few times with hot soapy water.  Then I filled it about half full with more hot soapy water and duped about 30 nuts in the tank, closed the lid and shook it around for about 20 minutes, turning it in different positions periodically. 

This is supposed to help knock loose some of the crusty junk stuck to the tank and wear down some of the large rusted areas.  After doing this, I emptied out the tank, and rinsed everything out of the tank a few more times.

Next, I plugged the bottom of the tank, where the petcock (fuel valve) threads on with a piece of rubber and hose clamp, and poured a gallon of Evapo-Rust into the tank.  I’ve never used Evapo-Rust but Rick Dale from American Restorations uses it, so it must be good.  

I let this sit in the tank for a few days, re-positioning the tank each day so that solution could make contact with every insider surface to dissolve as much rust possible.  

This worked really good to dissolve the rust, but there were still some greasy sticky chunks that did not want to rinse out. 

To take care of that, I sprayed a lot of heavy duty degreaser and high pressure water from the garden hose into the tank. 

I rinsed and repeated a few times until it looked pretty clean inside.

Next step was to dry the tank out from all the rinsing, so I could apply the chemical sealer.  It was a humid summer night so I used a heat gun in attempt to accelerate the drying and enjoyed a beer while I waited.

The sealer I used was from KBS coatings, called Gold Standard. I picked this because I used their brand of rust seal paint when I refurbished the frame, and I was pleased with the results.  To apply it, you simply plug the openings and pour the whole can into the tank.  You have to sit with it for 45 minutes to an hour and slowly roll and turn the tank so an even coat is applied over all the surfaces.  At that time you dump the remaining sealer out of the tank then let it sit with the cap open for a few days while it cures.  

The results were pretty good and the tank is now fresh and clean inside.