Modern fuel

I’ve done a quick search on the forum but not come up with anything about the increased volume of ethylene in petrol and the problems it can cause to plastic tanks. I’ve probably missed something but should I be worried and is there a solution to the blistering I’ve read about? So far no obvious problem with the Le Mans…

If you are worried take a look at the Frosts fuel tank sealer for bikes it works I did a V50 tank that had a linhole in it. BUT you have to follow the instructions TO THE LETTER

I have so far had no problems with the tank on my 2002 V11 Le mans … Although there have been some places where plastic and even metal tanks have been damaged.

In a nut shel Ethanol damages:-

Plastic AND Steel tanks
Fuel lines
fuel filters
Fuel pumps

It is well worth replacing fuel lines with ethanol proof ones as it does eat the fuel lines away. Had to change the ines on the V1000 and Annies Virago.

Same with the filters, the gauze on the fuel taps of the V1000 had literally rotted to nothing.

In fact IF they ever put 10%+ ethanol in fuel here ALL cars will need to have stainless steel fuel tanks OR get the old tanks lined.

Frosts can’t be used on non-metallic tanks apparently

Sorry if this has been done to death already, but this is my first post.

A couple of years ago I bought my first Moto G, a 2009 V1200 Sport, black, two valve (with black clock faces) from a dealer in Exeter. Tidy machine, added panniers etc and used it for a trip to S France, local trips and some commuting - irregular use. Great machine to ride, return each time with a silly grin, sails through the MoT and all fine until now.

Its always garaged but in the summer i noticed some bumps quite evenly distributed across the area of the tank where your knees go and thought it was apart of the design that I had not noticed before - its probably an age thing ! Didnt get to use it for a few months due to work and life in general, but kept it charged up ready to go.

On a couple of occasions I did wonder if the fuel level was dropping when it was not being used, and there is always a bit of a fuel smell about the top of the tank which I put down to a poor seal on the filler, not so sure now.

Went to look at it yesterday to prep it for going out today and the tank has caught a nasty rash, all over ! - and the clearance between the tank and the handle bar clamps appears to have closed right up - a quick google suggests ethanol in the fuel is to blame.

It looks a bit sad now. Is there a solution to this please ? , as ethanol is sure to be in fuel for good now, probably in increasing concentrations, so buying a replacement new or second hand tank will probably result in the new tank being similarly damaged in due course.

Are any aftermarket tanks available in a more suitable material, or is the only option getting another tank and epoxy lining it ?

I take it that flatting the tank down and respraying wont be a lasting solution.

Hi and thanks,

Chris, Wiltshire.

Unfortunately the tank blowing seems to be a well known problem, I`ve not had my 1200 Sport long but removing the tank proved to be a mistake as I had to elongate the rear mounting hole just to replace the tank. My tank had expanded enough to bring the bars in to contact at full lock. There seems to be no known cure apart from sticking tank in to a freezer before remounting it. The main problem is that anything but a new tank could present the same problem with the cost being astronomic


I have a Breva 1100 and each time I removed the tank for servicing it seemed to get more difficult to replace, until it eventually I had to use excessive force to make it fit, due to expansion.
I remember reading somewhere that if you drain the tank and leave it to air for a few days it will shrink back to it’s original size. Therefore, on the grounds that it cost nothing, it’s worth a try.
I did, it did and fitted perfectly.

That is worth knowing!

Go to: “Small Block V Twins inc V7iii and V9” and search: “plastic fuel tanks”.

You will find numerous posts !

The whole fuelling system has to be “ethanol proofed”.

Easy way to tell how much Ethanol is in the petrol your buying is to look by/above the pump where it’s holstered, it should have a black circle with E5 inside it, or from September E10.

Another point to be aware of if you go on to mainland Europe, is that while petrol pumps are colour coded here, green for petrol, black for diesel, that is now no longer always the case on the mainland and instead you need to look out for the labelling, ie E5/E10 for petrol or you might end up filling up with diesel, which could be problematic, lol

I elongated the mounting hole on my plastic tanked V7 Classic. That was a disaster, as I removed to much material and broke through to the tank. The petrol gushed out. I had to buy a replacement. I PXed the bike for a later V7ii with a steel tank and greater capacity.

Those plastic tanks are/were a disaster. MotoGuzzi should be replacing all plastic tanks with steel tanks, free, or at least at a heavily discounted price, on the grounds of safety.

I filled up at Tesco, Bar Hill, on Monday. The standard 95 Octane fuel was E10. The premium grade 97 Octane is now E5. So, my first fill up with E10.