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Ethanol Tank Swelling

As the owner of several bikes in the U.S. that have plastic tanks, including two Ducati and a V11, I'll add what I know about plastic tanks and ethanol. The plastic tanks on European motorcycles are made by Acerbis, an Italian plastics company. They are made from a type of plastic known as PA6 nylon. If you look inside your fuel tank, its a white plastic. The manufactures love it because it holds glossy paint so well and can be molded into complex shapes. If your bike has a painted plastic tank (not a shell, or cover) you can be certain it is PA6 nylon and (sooner or later) WILL be affected by ethanol in the fuel. The tanks are "roto-molded" meaning they pour liquid plastic into a mold, and then rotate it like a chicken on a rotisserie to coat the inside of the mold. Once again, shine a flashlight into your tank and you might see small drips and runs like candle wax, from this process. This can and does lead to varying wall thickness which explains the bubbles and blisters that appear. PA6 nylon is "hygroscopic" meaning it absorbs water. This is what leads to the expansion and deformation of the tanks over time. I think I read where PA6 nylon can absorb up to 10% water by volume. Every used Norge I've looked at shows some swelling, which can be seen by turning the handlebar to full lock, and the top triple clamp will come into contact with the tank before it hits the metal stop. There are usually two small chips in the paint at the front of the tank where this happens. Since the amount of moisture the plastic absorbs is limited, the swelling does stop. Your tank won't grow forever, like some tumor! But getting the mounting holes to line up after the tank has been removed for service can be a real pain sometimes. The manufactures have slowly phased out some (but not all) PA6 plastic tanks for a different material, black in color, which will not hold paint, hence the trend to fake plastic "covers" over the tank on many bikes. Hope this long-winded explanation sheds some light on the subject.


Great explanation to how and what is used to build these Acerbes tanks. BUT, I can tell you from experience, MV Agusta is using a new plastic, or maybe a coated plastic that has solved the issue (so far). I received a warranty tank from MV Agusta for my 2014 Rivale and the tanks look identical, inside an out..... both have that same "milky" looking plastic inside the tank. I was expecting something different, but nope! The only thing different was the new tank had a molded "E" on the back side of the tank, I suspect for "Ethanol" and that "E" had a gray circle around it. It's been 1.5 years since it was replaced and it still looks perfect. The original tank got blisters within a month of ownership. So, Acerbes definitely has a new material. Hopefully all the manufacturers start using this new plastic!

We're forced to run E10 here in Southern California, so to those that say they don't run E10 because of the issues described - congrats for having it available to yourself, we don't have that option and it sucks! I hear Europe is soon to receive E10. I feel sorry for you guys. Be prepared for headaches.
 
We've had e10 here in Germany for years, but we also still have e5 and if you're prepared to pay for it, ethanol free. Personally, I don't feel the few cents less per litre for e10 is worth it.
 
If I had a nickle for every Ducati rider that told me, "my tank is perfect." Unless you do 100 percent of your own maintenance you might never be aware of the subtle changes in your tank caused by ethanol. I remember hearing that exact line from a Multistrada owner until I parked my ethanol-free bike next to his and started to point out all the differences in the tank and panel mis-alighnment between his bike and mine. He didn't have much of a smile left on his face when I was done. Hated to be the bearer of bad news, but I don't think any plastic tank motorcycle is immune. The only difference is time and miles. Some expand a lot, some just a little...but it's there if you know where to look.
 
Resom- I hope your right. I know that the plastics can be treated or coated to make them impermeable, but of course the cost goes up. By now Acerbus is more than aware of the issues with E-10. Hope they have a permanent fix. Plastics DO have the advantages that, in the long run, they don't rust out like steel fuel tanks do. I don't really hold it against the manufacture, just our stupid useless government and the out-of-control EPA.
 
Plastics DO have the advantages that, in the long run, they don't rust out like steel fuel tanks do. I don't really hold it against the manufacture, just our stupid useless government and the out-of-control EPA.

Agreed. I have a Ducati 916 I bought brand new in 1995. The bike sat for 5 years in storage while I was away. I treated the fuel in the tank and filled it to the top, keeping all the fuel components submerged. When I retrieved the bike 5 years later I opened the tank and everything looked/smelled normal. I thought "great!". I then took the fuel pump out to replace the fuel filter and found the tank had rusted badly in ONE spot.....the spot where the water had collected from the Ethanol and fallen to the bottom of the tank. Another example of how this crap E10 fuel eventually destroys every tank it sits in.

It's a proven fact that the percentage of Ethanol contained within gasoline drops the fuel mileage by that same percentage, so remind me again how it's a renewable fuel? So frustrating! Rant over :lipssealed:
 
I have a 2017 Stelvio NTX which I bought new in Dec. 2017. I removed the evap canister right away however my tank shows several dime and nickel size bumps as well as some waves . Took the bike to Proitalia this last Saturday and they filed a warranty claim and by Tuesday they already had the new tank. Great service from both Proitalia and Piaggio!
 
It's a proven fact that the percentage of Ethanol contained within gasoline drops the fuel mileage by that same percentage, so remind me again how it's a renewable fuel? So frustrating! Rant over :lipssealed:

Absolutely! Ran E15 recently in my car for a few weeks because it was so cheap. Mileage in the car went from 36 mpg to 29. That is insult upon the injury of what that crap does to a fuel system in general with the muck that is created.
On my 1998 FJ1200 I can't even get the bike to run right with new fuel (E10) & have resorted to using race fuel with no alcohol at the cost of close to $16 per gallon. Now nothing but a track bike.
 
While I am not a fan of E10, I have been running it for a very long time now. Aside from some pimples in the paint of the wife's V11 I don't have issues with how my motorcycles run on it. I have Guzzi's ranging from an '87 V65 Lario to an '07 Griso. The carb's bikes are more likely to have an issue with E10. But carbs are easy to adjust, jets are easy.
I did have the E10 turn a snow blowers "fuel" line to taffy, but I put that down to the manufacturer using the wrong type of hose for fuel line.
In some places you can still by non-ethanol fuel. But around where I live it is hard to get and pricey when you can get it.
 
I have a 2017 Stelvio NTX which I bought new in Dec. 2017. I removed the evap canister right away however my tank shows several dime and nickel size bumps as well as some waves . Took the bike to Proitalia this last Saturday and they filed a warranty claim and by Tuesday they already had the new tank. Great service from both Proitalia and Piaggio!

Great to hear they took care of it for you! Did you run fuel with Ethanol or Ethanol Free fuel in the 1.5+ years you've had the bike?
 
I have a 2017 Stelvio wich I purchased in FEB 2018 I had it in the garage and came back from vacation in JULY and my tank had a bunch of cracks in the paint and swelling. I think its from the charcoal cannister set up not allowing the tank to vent properly (Tank pressurizes when hot) anyways got a new tank under warranty and took all the cannister crap off it and have since NO PROBLEMS.
 
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