Acerbis 4.1-Gallon Large Capacity Gas Tank

What it is

• A large capacity tank for KTMs.

The Acerbis 4.1-gallon large capacity tank is a replacement fuel tank that basically doubles the gas you carry when full up from the standard 2.2-gallons. It integrates the radiator shroud covers into the tank and mounts up using the stock attachment point.  It’s filler neck is bolt-on allowing the use of a standard screw-on cap (included) or a dry-break quick fill if desired. The tank does not come with the fuel pump but has the parts required to fit the one from the stock tank into the Acerbis tank. On EXC models you must remove or relocate the evaporative emissions canister. Most cooling fans fit with the tank but some radiator protection can get in the way.  It is available in natural or black in color. There is also a 5.3-gallon version of the same tank that is also wider. Additionally KTM Hardparts sells the same 4.1-gallon tank in KTM Orange.

How it works

• Simple installation using stock mounting points
• It isn't that wide considering how much additional fuel/range you get.
• Additional protection for the radiators without compromising the cooling.

Installation of the tank is simple and takes about 5-minutes maximum, if the fuel pump is installed in the tank. You are looking at about 30-minutes for that procedure. The included illustrated instructions might confuse some, they are that simple. We actually bought a second fuel pump and fuel-line connector (KTM P/N  5850701050030—fuel clamp, 78107088000--fuel pump) so swapping tanks is just a few minute task.  Having the large opening at the fuel fill attachment opened up made the fuel pump install a snap since you can get your hand inside the tank to place the fuel pump and exit line. Just make sure to clean out any manufacturing residue from the tank first, our tank had some foam pieces inside it. It fits on with the standard cooling fan on the 500EXC and there is room for most types of accessory radiator bracing provided they don’t have structure behind the radiator. We had to relocate the emissions canister to down along side the upper chain guide as there is no room for it with the large tank. This is not an issue on an XC-W.

The tank attaches on the two center frame downtube slid-in mounts and with a 6mm bolt on top of that frame rail, just like standard. And from 2013 and on, the junction of the tank and the side panels in not a perfect match, but it is minor. The radiator shrouds are now part of the tank which adds a bit more protection to the sides of the radiator as the tank is much stiffer than the plastic shroud is. It is also noticeably wider. Not really just at the seat, where it is roughly the same. But as it goes forward and then outwards where the shroud would be, it gets progressively wider to about 2-inches wider on each side alongside the radiators. When riding the bike, the more you grip and squeeze with your knees when sitting, the more a rider will notice this. Standing you do not really notice the tank is bigger and many thought it actually had better grip points for their knees. For the many who dislike the push-button KTM gas cap, the screw-on style of the Acerbis is welcomed, but be careful not to cross thread it. Catching the first thread can sometimes be tricky.

Giving an additional 2-gallons of fuel basically doubles the range of the bike. With the stock tank on the KTM 500EXC we were able to squeak out 100-mile rides on a regular basis. Now can pull off 200-miles if we are careful. A safe range is easily 180-miles with the Acerbis tank. The added 12-pounds of fuel is noticeable and not all in a bad way. When full and riding dirt roads, the bike is actually more planted and felt like it vibrated less. But in the bumps and when in very technical riding you can feel the highly placed pounds. But we also learned that when the extra gas was not needed, by filling the tank ½ or ¾ full the weight wasn't noticeable, just the width. Then it even carries that gas lower than the stock tank does. And since the tank can be swapped back to the tiny standard one in minutes (if you have the fuel pump in it already), that is always an option.

Overall this tank is a great fit and does an excellent job of adding a lot of fuel without becoming too obtrusive.  We’ve crashed with it and it resists damage as good as any tank and also has protected the radiators in some slow speed tip-overs. The natural color easily shows where the fuel level is and resists discoloration as good as any if our experience with previous natural colored Acerbis tanks and running pump gas is any indication. With different fuels you may have different results. The price is fair for a such a complex part and you’d easily pay a lot to not be out of gas a long way from nowhere.

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