Article By: Wayne At Wicked Willy’s Choppers
Originally Published In The May 2011 Issue Of Cycle Source Magazine
In this section, we are going to build a gas tank from scratch. I will be using 18 gauge sheet metal and our tank will be a little radical because instead of sitting on the top of the frame, it will actually fit between the frame. You can’t order a tank like this from a catalog, so it will be done the hard way. For you first time tank builders, let me just say the tank shown in this section took around thirty hours to build. Also, all welds will be done with a TIG welder so we get a good weld to seal the tank.
The first step to building this tank is to turn two bungs out of cold roll round stock. They are threaded with a blind hole so no gas will be running out around the threads. Also, I’ll make them beefy enough to take the vibration of the bike.
Once I have the bungs machined, I bolt them into place. You can see when I built the frame that I welded in hidden bungs to mount the tank to. It’s a good idea to try and think of all the things you want to do from start to finish. This will keep you from going back and making changes. Also note here that our tank will be going between the backbone and the lower bar. When I build the tank, I will want the top to cover half the backbone to hopefully make a nice neat job.
To get around my backbone, I took a piece of 2 inch tubing and arc it into the shape of the backbone. Here, I am using a manual tubing roll bender. Trust me, this is a sweet tool. Take your time and check so you only do this once.
This is my tubing that I arced and split. I only need the bottom half to make the channel for the backbone. All I did was take a grinder with a cut-off wheel and split the tubing. I then placed it in the frame and cut the length I needed.
Shown here are the channel I made, and the strap that the bungs are tack welded to. This will make the very top and bottom of my tank. Notice the rod I tacked in to hold my parts together as I build my tank.
Once I have cut my sheet metal for the panels for the top of my tank, I use a metal shrinker to roll the outer edges to give it a bow. This is a slow process but works nicely.
After I use the shrinker, I move to the English wheel. I’ll use this to finish the bow I am looking for in the top of my tank. Watch your fingers and have at it. This will make a nice clean job. You can hammer it if you like to speed the work up. I chose not to, because trust me, you have to roll all your hammer marks out.
Here are the top panels of the tank tacked in. Notice how smooth the English wheel kept the panel. You can now see the arc I was after. The panel not only arcs back but they arc to the side making a dome type shape.
Now, I have tacked my side panels in. Unlike a tank made to sit on top of the frame, I am building this one in the frame so everything will fit right. This tank has to come out after I build it so tack and fit is very important. This is the top of the tank. I am checking to see if it lines up and that it will come in and out nicely. Make sure to use enough tacks so that the metal will not move when you start welding the tank.
Once I have my tank tacked up and the fit is what I am looking for, I remove it from the bike and weld it up. I use a TIG welder to do this for two reasons. Number one is to control the heat so I can keep my tank from warping. The second reason is that TIG makes a cleaner weld where you do not have to worry about leaks. Now trust me, if you’re just starting out, welding a gas tank is not the job to learn on. It takes lots of practice and skill to weld up something like sheet metal to hold gas or oil. If you’re making your first tank, tack it up and let someone that does a lot of this type of welding do it for you. I usually do 3 to 5 tanks every year for do-it-yourself guys. Don’t be too proud to ask for help.
Here is a front view and top view of my gas tank. I am now ready to add filler and a petcock bung. I will show you how to do that in the next installment. If any one has any questions about our tank we have built, e-mail me through our Web site www.wickedwillychoppers.com or call me at the shop 828-303-0422.