How to remove rust from a motorcycle gas tank
One of the benefits of being able to work on motorcycles is that, in general, you can find them quite cheap when you need to work on them. Usually a bike that needs work has been idle for a while, usually with an empty tank. This means that over time the rust has taken over, as was the case with a 1981 Honda CB650 that I had purchased. To say that this thing had rust was an understatement; it had chunks of rust on it. Fortunately though, the tank wasn’t leaking through holes or anything and it was completely solid. Now for the fun part! I will explain the process of removing rust from a motorcycle gas tank. Like I said, this was done on an 81 ‘CB650 so it’s designed for that, but I’m sure it will work on most other bikes.
What you will need:
- Acetone
- Distilled water (it is important that you only use distilled water)
- Two stroke oil
- A length of chain 4 to 6 feet long
- Rags
- Something to plug the fuel outlet (I used a small piece of hose, a small rag, and a piece of black tape)
IMPORTANT NOTE: ACETONE AND RUBBER DO NOT MIX! If you use rubber to seal the fuel outlet, replace it each time you drain the acetone mixture, as the acetone will consume it.
At this point, I am going to assume that you have the gas tank off the bike and that it is empty. Here is a step by step.
- Plug in the fuel outlet and make sure it is sealed
- Fill the tank halfway with acetone and let it sit, turning occasionally.
- Wait all night
- Shake the tank and pour the acetone / oxide mixture into a bucket
- Refill the tank to half with acetone and this time release the chain
- Shake the tank frequently and vigorously. The chain will remove the remaining rust.
- Pour the acetone / oxide mixture into the bucket.
- Fill the tank with distilled water and empty it. Do this until only fairly clean water comes out and no rust is heard around. I put a hair dryer in the fuel hole and dried it immediately after
- Fill the tank approximately ¼ full with two-stroke oil and shake and then drain.
- Dispose of acetone and other nasty chemicals properly
I highly recommend installing an in-line fuel filter in the fuel line between the tank and the carburetor. It will filter out small particles and keep them out of the fuel system. This system worked for me, my CB650 ran like a dream after cleaning the tank this way! The next step is to give the carburetor a good clean.
