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How To Narrow A Motorcycle Gas Tank

This article originally appeared on the LFTC forum, and was written and photographed by Flat Iron Mike. Thanks to Mike for letting us repost his real nice how-to on cutting down and narrowing a Sportster tank.

In my leisure time (?!) I've been wanting to cut down the Sportster tank I've been threatening to do for some time now. It's not some high tech execution, fancy or smooth, but it's the way I do it with the tools I have. So here goes....

Did I mention I hate Sportster tanks on anything other than Sportsters? Cutting 2 1/2" from the middle and 2 1/2" up from the bottom with the angle grinder.

Jon Volk was kind enough to 'make ends meet' to determine if I could continue. Thanks, Jon! Oh yeah, I'm trying to salvage the paint on this - the factory hand painted H-D lettering. Next up is fabbing the new tunnel/bottom. Looked in McMaster Carr, but only found 16 ga. (crap!). Bent the tunnel over a piece of 2" sched 40 pipe, but the 2 90 deg. bends were impossible by hand. Stopped by a fab shop around the corner and borrowed the 60 ton press brake for only 20 clams (?) Next, I cut the tunnels in the tank and bung hole (tee hee hee) using borrowed tools (nibbler and electric snips).
On to the bottom / tunnel. used the electric snips, dremel and belt sander to cut and shape the bottom. Also drilled the petcock (tee hee hee) fitting.
I know, I know, basic stuff, albeit interesting, due to my caveman technique. Made some tongues to mount the gas tank to the backbone. All I had was some 1/8" laying around, so it's a beefy set of gas tank mounting tabs.
Front and rear... looks okay..
Speak with forked tongues..
After a visit with Jon Volk for final welding, the turkey is ready for some rattle can over the bare metal bottom and 'scar' tissue. Final capacity is about 2 gallons. Hey, looking like a roller...


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