This Old Gas Tank. Part 1

This is all about what it takes to find and repair an old gas tank and make it usable again for your project.

So I had a customer come in and they wanted to customize a TW200 Yamaha. Not really my thing at all, but I can handle it. Changing up the gas tank was one of the top things on the list. It involved getting a tank, from 1978 and fitting it to the frame, which is 2001 ish. I thought it would make a good article so you can see what is really involved in doing a job like this the right way.

Step 1) Find gas tank.

This maybe easy, or not so easy, it depends on what you are looking for. In this case I think I lucked out because I found what I wanted and it was in good shape for what it is. The biggest thing with gas tanks is to find something usable that isn’t a rusted out relic …aka .. piece of junky shit that should have been thrown out years ago. Japanese tanks are very hard to find in good shape because they are thin and rust out easily. Sometimes they can be welded, but it is a lot of work. So when picking a tank the inside of it is the most important thing to look at. On this particular tank I lucked out. It was probably cleaned with muriatic acid by someone and it was a nice raw metal on the inside with a little bit of what seemed like blast material left. All in all the tank is real solid.

Being a 1978 125cc dirt bike tank it had some dents. One sort of big one on the side and a bunch of small ones. This is to be expected. the fact that there wasn’t any holes or tears was great, and also it came with a gas cap and petcock.¬† Just those 2 parts can add a lot to the price of a project when they are somewhat obscure parts like these. In this case there isn’t really any aftermarket parts companies making anything as far as I know, and if they did the new stuff is sure to be expensive. Heck just a used gas cap for this tank was generally $50.00. That’s a lot of money for a cheap plastic cap.

old gas tank repair
The find. A 1978 DT 125 tank. Is it any good?

old gas tank inside view
Nice and clean looking on the inside. Too clean to be original, but it ended up real nice. That’s a lot less work to be done! It was clean enough to be coated.
1978 yamaha project tank
It has some dings and dents, but you can see it still has a nice shape to it overall.

repair motorcycle gas tank
The biggest dent. Since we don’t know the story behind it, we’ll just make one up. They were riding through the woods and hit a tree kinda sideways that was about 4″ in diameter.

Step 2) Judging the tank from pictures and maybe talking with the person selling it.

It can be really hard to tell the condition of something from just pictures. I got lucky and there were good pictures of this tank and it was a seller I have worked with on several occasions, whom I could trust. I’ve been disappointed before, whether it was from dishonest sellers, or just someone who honestly didn’t know something, or sometimes shit just happens! So if you can’t physically touch the tank before buying, look at pictures and ask questions and above all… know about what it is you are dealing with. Knowing the in’s and out’s of the part your looking for is some of your best information. In this case knowing that gas caps aren’t really readily available, petcocks can be a real hassle, and most important was knowing that Japanese tanks are thin and can rust out bad. More on that later. It’s going to be a long article, I took a lot of pictures¬† : )

EBay is a good place for finding stuff. If you do use EBay look at the sellers rating and how many transactions they have. Occasionally you have to buy from someone that is new to EBay, but generally I have found that most sellers are honest. In this case, I found the seller on EBay, and have done business with them before and started doing business with them through their regular shop and not EBay, so a quick email of what I’m looking for got some results.

bottom of vintage motorcycle gas tank
A picture of the bottom of a tank is important for rust holes. Water will lay in the bottom of tanks and pretty quickly rust a hole in it, especially along the seems of Japanese made tanks. (as well as others that use the same manufacturing process)