Hi everyone got a problem with my fuel tank on my 03 290. My bike has been hardly used over the past couple of years and the fuel tank has swelled and gone really flexible i think it has been caused by leaving a small amount of fuel in the tank and the vapours have attacked the nylon type material that forms the tank. Now l know the tank is scrap but has anyone experianced this before and also does anyone know of any trials breakers

Are you saying that the tank was once rigid and over time has become too pliable (underneath)?

I buy bikes when they're 1 year old (approx).

I've had a 2001,2003,2004 and 2005 and the tanks were much more rigid on the older bikes than the new(er),nothing to do with how long I had owned/stored them...saying that though..the oil companies are putting all sorts of chemicals in petrol today?

The tank has all ways been flexible but now even more so it has also grown in length and width to the point of being difficult to remove and refit also fuel cap is difficult to get on and off

Modern living ..planned obsolencence?

I had noticed this a bit as well in earlier years, but never had the bikes long enough to be an issue. One can actually get a bit of adjustment out of the top post on the earlier bikes.

It was always suspected, but on the '07 I have pornographic evidence of the fact! The tank has grown about 10mm in length and is getting really difficult to cram into the hole! Add it is indeed to the point where things are getting critical!

I am not sure if this is just a normal reaction of nylon to gasoline, or a reaction to the other stuff in the fuel, nor am I sure if it can be corrected and shrunk!

Do we have any local plastics engineers that could enlighten us, seems we did at some point?

My 2000 tank has a tightness issue. Bloody pain in the a*** to get fitted properly. As an adjustment fix I ovaled out the hole that the top mounting screw fits into and that gave it enough space to snugly fit into place. I don't know what other years have for the top mount bolt to go through but the 2000 has a flat plate between the frame rails. Hope this makes sense.

I had noticed this a bit as well in earlier years, but never had the bikes long enough to be an issue. One can actually get a bit of adjustment out of the top post on the earlier bikes.

It was always suspected, but on the '07 I have pornographic evidence of the fact! The tank has grown about 10mm in length and is getting really difficult to cram into the hole! Add it is indeed to the point where things are getting critical!

I am not sure if this is just a normal reaction of nylon to gasoline, or a reaction to the other stuff in the fuel, nor am I sure if it can be corrected and shrunk!

Do we have any local plastics engineers that could enlighten us, seems we did at some point?

Spanish Nylon?

I am too familiar with this issue. I bought a used 2004 290 and the fuel tank had grown and was pushing the rear fender back and the tank was very tight in the frame. The bottom of the tank was very soft and flexible and it was rubbing on the engine mount and I was concerned that I was about to become a very "hot" rider! I bought a new fuel tank just before I sold the bike and I bought a new 2009 Sherco 3.2.

I had my 3.2 about 6 months and things were going great - then I noticed the fuel tank was getting more flexible and was growing. It was starting to push the fender back and it was very snug in the frame rails. The fuel petcock was leaking as the mount was too flexible and not pushing against the 0-ring tight enough to seal. I had to get a new tank after just 6 months.

The area I live in has EPA mandates that require all stations to sell fuel that contains 10% ethanol - and I believe that is what is causing the fuel tanks to swell and become flexible. I talked to one of the delivery truck drivers and found out that the bulk plants that distribute the fuel mix in the ethanol just before delivery to the gas stations. They do sell gasoline without ethanol blending to farmers to use in their equipment, as the blended fuel does not store well in the elevated tanks the farmers use. I was able to buy some of this fuel prior to blending with ethanol and I am now using it, the distributer says they have a lot of companies that do landscaping that buy this fuel for use in their lawnmowers and chainsaws as it stores better than the fuel with ethanol blended in. VP fuel now makes a 94 Octane fuel that is intended for use in landscaping equipment that does not have ethanol in it, and I am probably going to buy some of it for my Sherco.

Edited February 22, 201016 yr by 1oldbanjo

I am too familiar with this issue. I bought a used 2004 290 and the fuel tank had grown and was pushing the rear fender back and the tank was very tight in the frame. The bottom of the tank was very soft and flexible and it was rubbing on the engine mount and I was concerned that I was about to become a very "hot" rider! I bought a new fuel tank just before I sold the bike and I bought a new 2009 Sherco 3.2.

I had my 3.2 about 6 months and things were going great - then I noticed the fuel tank was getting more flexible and was growing. It was starting to push the fender back and it was very snug in the frame rails. The fuel petcock was leaking as the mount was too flexible and not pushing against the 0-ring tight enough to seal. I had to get a new tank after just 6 months.

The area I live in has EPA mandates that require all stations to sell fuel that contains 10% ethanol - and I believe that is what is causing the fuel tanks to swell and become flexible. I talked to one of the delivery truck drivers and found out that the bulk plants that distribute the fuel mix in the ethanol just before delivery to the gas stations. They do sell gasoline without ethanol blending to farmers to use in their equipment, as the blended fuel does not store well in the elevated tanks the farmers use. I was able to buy some of this fuel prior to blending with ethanol and I am now using it, the distributer says they have a lot of companies that do landscaping that buy this fuel for use in their lawnmowers and chainsaws as it stores better than the fuel with ethanol blended in. VP fuel now makes a 94 Octane fuel that is intended for use in landscaping equipment that does not have ethanol in it, and I am probably going to buy some of it for my Sherco.

I am unsure if this is related to the alcohol or not, or just simple HC permiability. What I would like to know is if they will shrink if dried or baked out? It just seems to me this has always occured even prior to the alcohol laced fuels.

Had a talk with 1 of the moulders next door today & he agreed that nylon is normally very stable but a lot of the things that were put in fuel as a substitute for lead are as bad for the nylon as they are for our health. The alcohol blends just make things worse but their effect is less certain due to the small amounts mixed in.

As a side note motorcycling australia investigated using E85 fuel for this years superbike championship & abandoned the idea due to it becoming apparent that too many parts of the fuel systems not being compatable with the alcohol leading to major safety concerns. It wasn't only the plastic parts that they were worried about