How can I tell if my motorcycle has a rusty gas tank?

Question

This is in reference to my previous question: http://answers.yahoo.com/question/?link=best&qid=20070716190444AA8dC3r&r=w&pa=F5xxBXHpPmKSlmhy00sKmV5E1D961yCyRKpZ.krKiNqYONeGWJ2XxA--&paid=choose_best

The answer I found most informative reccomended using a fuel tank cleaner to clean rust/gunk out of the gas tank and seal it. When I emptied the gas tank there was no debris in the fuel at all. When I say none I mean NONE. Visual inspection of the fuel tank, the inside doesn't look rusty (as much as I can see from looking into the filler) Can you usually see the rust or should I just assume its there and hidden in some part of the fuel tank I can't see? I can probably see about 1/3-1/2 of the tank by looking at it every angle I can.

The bike is a 1980 Kawasaki KZ440 for reference

Answer 1

As to a couple of the other answers here, rust forms in the gas tank of older bikes normally because of storage. Water condenses out of the air during temp change and into your tank, oil floats on water, so it generally goes to the bottom of the tank, and sit there forever, because no one runs the tank all the way down.

Based on your previous post, and the fact that you saw nothing on the petcock filter, you are probably fine, and don't have rust.

While an inline filter (especially one that is clear that you can check occasionally for debris) is a very good choise for making sure that your carbs don't get gunked up with that stuff coming out of your tank. But what it DOESN"T do is protect your petcock. Some older bikes have a horrible time trying to find a petcock after thiers gets screwed up by debris. Anyway if you petcock is partially blocked you get a very weird running bike as well.

Like I said, sounds like you are good, if you saw nothing in the petcock screen (that will catch the big stuff, but probably not the smallest stuff).

Other cleaning techniques I have heard of in case you want to really be sure is to use pennies to rattle around in there along with a solvent, then dump the pennies and solvent out and check for rust flakes. Then a quick rinse with gas and reassemble.

This is a real common problem for older bikes and restoring old cars. Improperly sealed tanks can also come back to haunt you as the sealing materials come loose and totally clog you up.

Answer 2

Cleaning Rusty Gas Tank

Answer 3

Somebody's bein' dumb with the thumb again.
You really do have a lot of good answers already.
It sounds like you already have a very clean tank.
The worst of it would have settled at the lowest part of the tank. That's usually but not always (alas) the petcock.
If your tank is clean to your satisfaction, do not bother to seal it. The sealants work well on new tanks. I have seen problems when people try to seal old ones. I had such a tank once, what a nightmare.

Answer 4

Well if you cant see any runst in 1/2 of the tank - chances are pretty good that you have a clean tank.

Run a quality see-through filter just to be sure.

Flush it out and get on for a ride.

Answer 5

Rust and any other particulate debris would be caught in the filter. Examine it for rust. If the filter's clean, you're most likely okay. The question I have is why do you think you have a rusty gas tank?

Answer 6

You have a lot of good answers here. I had a rusty tank, (saw rust in filter), and used all the tricks to repair. First I inserted loose screws with kerosene, (more abrasive than marbles) to remove rust....worked okay. Second I rinsed out with gasoline, wasteful, but a good way to get out debris and leave a dry tank. Third, I used Kreem to seal the interior of the tank. Kreem is nasty stuff and you have to be prepared to roll the tank for several minutes to coat the whole interior. You may want help with this as your arms will get plenty tired. After that, I reinserted filter (pain in the butt because Kreem made opening smaller than before), reattached hoses (also a pain it the butt because Kreem had to be drilled out of openings where it had dried them closed). The whole process turned out okay, but I'd probably just buy a new tank if I could get one that matched my ride. I had to go the Kreem route because I just had all my parts custom painted. Good luck.

Answer 7

drain you tank and let it sit for a few days with the cap off the the fumes will die down, get yourself a telescopic mirror and a flashlight and see if you get a better look. their is a product called kreem for metal tanks that comes with a acid to remove rust and a coating that will seal your tank from rust. good luck

Answer 8

rust is not a problem on the inside of a gas tank unless a poor cap has been on or worse a rag. It takes exposure to "air elements" to cause this problem.I think you are overprotecting.Buy a new cap and seal, and you will be preventing any future problems with rust.If your cap and seal are good then your ok right now.

Answer 9

Drain the tank and put some marbles in it. Shake it around real good with the marbles and kerosene in it. That will get the debris out if there is any. If there isn't any, it won't matter and at least you can rest easy.

Answer 10

If you cant see any rust its probably fine, I would guess that the tank is made out of aluminum which does nor rust anyway. (Most modern bike tanks are.)