by Owen Mould

Created on: December 18, 2008   Last Updated: February 14, 2009

HOW TO PUT A 5.5 GALLON FUEL TANK ON A HARLEY-DAVIDSON FXR

INTRODUCTION

The problem with many Harley-Davidsons, especially older models, is that the fuel capacity of the OEM tanks is wildly unrealistic
for day to day practical use or even the occasional long-distance trip. This was never a problem for most folks during the boom years of the past, but now that we are looking at some tough times, more and more owners are looking to turn their motor vehicles into more practical and usable tools.

As of this date, only one company makes larger tanks for the popular Harley FXR with a specific eye toward supplying greater range out of a tank. The cost for one of these tanks is priced for the showbike customizer, not for the average rider, hence the tanks remain prohibitively expensive.

As it turns out the answer came from Sporty riders, who have the pleasure of enjoying an 80 mile range from their 1.5 gallon tanks. Better MPG for sure, but why the devil a useless 1.5 gallon tank! Their solution is to buy a used tank made for the FXR model, giving them a whopping 3 gallons right away.

But for the bigger FXR, there are few choices, as the bike wants a 5-6 gallon tank. Because the big backbone of the FXR frame rules out many choices right away, we looked to see what others had done. Turns out there are several people who have put 5 gallon tanks on FXRs and actually got good looking results.

This article will describe how to put a larger tank on a Harley, with attention to keeping down the costs and preserving at all times the ability to restore the bike back to the way it was prior to modification.

This HOWTO applies in significant measure to other models of Harley as well, as it goes over some of the gotchas a shade-tree mechanic is likely to encounter.

HOW TO PUT A 5 GALLON FUEL TANK ON AN FXR

There are three options to do this.

1. Weld on mounts for split side tanks for just about any machine and there you go. Or have your welder add appropriate mounting tangs to the replacement parts, using an old FXR tank as a guide for placement.
2. Modify and mount a Dyna tank from the mid-nineties, carburetted versions.
3. Modify and mount an old style Electra Glide tank, model FLHT.

I elected #3 as this tank had the right tunnel dimensions and the closest mount points and equalization tube arrangements. Also, I proceed from a basic rule of thumb all modders should follow: Modify the add-on part first, NOT the frame or engine block.

STEP ONE: PREP THE TANK

PARTS
Two Kreem tank prep kits
Two gallons

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