Forks hitting tank

[Bubb]

I have searched around and have not seen any one else with this problem. When making a tight turn or turning the bars the tubes will hit the extreme font of the tank on both sides. Any help in curing this problem would be appreciated. Thanks

[The Monkey]

I have searched around and have not seen any one else with this problem. When making a tight turn or turning the bars the tubes will hit the extreme font of the tank on both sides. Any help in curing this problem would be appreciated. Thanks

 

Hi Bubb, is the tank settled onto the forward mounts properly? If it isnt it will be too high and possibly cause the clearance issue. good luck Cam

[edge]

If the bike has been down, I would check the bottom tripple tree stearing stop lug(s). If the tank is set properly, my guess is the stop broke off if tank is set propperly. Also if the stearing stop lug is gone/munched, I would look at the damper too, since it has been hyper extednded/compressed in the process.

[Greg Field]

It is also possible that the tank is swelling.

[Guest ratchethack]

My tank had expanded to the point many years back where it first began contacting the side covers, then interfering more and more substantially with the front mounting points of the rear carapace when removing/installing the tank, then hitting the fork stanchions at full lock, and it's evidently still expanding. I shimmed it up at the rear with a 1/4" nylon washer to stop it rubbing away the side covers. Beyond that, not a whole lot more you can do without welding up the fork stops.

[Dan M]

It is also possible that the tank is swelling.

 

 

+1

Mine is at the point of rubbing the side covers like Ratchet described.

[BRENTTODD]

My bike and Fuelcoolers bike the forks hit the tank when on the stops, I thought that was just the way it was

[Greg Field]

My tank had expanded to the point many years back where it first began contacting the side covers, then interfering more and more substantially with the front mounting points of the rear carapace when removing/installing the tank, then hitting the fork stantions at full lock, and it's evidently still expanding. I shimmed it up at the rear with a 1/4" nylon washer to stop it rubbing away the side covers. Beyond that, not a whole lot more you can do without welding up the fork stops.

 

 

Commendatore:

 

Had alcohol-laden fuels been made commonplace in your area before the swelling occurred?

[Guest ratchethack]

Commendatore:

 

Had alcohol-laden fuels been made commonplace in your area before the swelling occurred?

Yes. Many years before.

[OldButNotDead]

Great. Another joy of growing old - my aging tank appears to be swelling and getting longer - no viagra needed.

 

I thought I was hallucinating when I removed, then replaced my tank for the first time this spring, and had to push it forward really forcefully to get the rear mounting holes aligned.

[Steve G.]

I've got to question this swelling fuel tank thing. I experienced side cover/fuel tank contact almost from new, clearly Moto Guzzi had not shimmed the rear of the tank properly. Can anyone here confirm if alcohol in fact swells plastic designed to carry and hold volatile liquids for many years?? I've got a container that holds pure wood alcohol [Methal Hydrate], they sell it by vast quantity, only using plastic containers.

And even if it did swell the tank, to the point that it bubbled out to touch the forks, then what's happening to the other sealing and resting areas? The thing would be hemoraging gas from every possibilty. As well, if the structure of the plastic tank is being compromised to such a degree, why isn't the the paint and decals coming off on your hands?

The problem surely lies with proper tank placement or previous damage to the triple tree stops.

Steve

[Greg Field]

I also question whether alcohol could do this, but something appears to be going on. I've never seen a tank on which this has happened, but folks here and elsewhere have testified to it often enough that I can't really doubt that something is happening.

[Guest ratchethack]

I've got to question this swelling fuel tank thing. . . .

Both "plastic" and "alcohol" are very large categories of often complex compounds, of which there are literally countless entirely unique varieties and mixable combinations of each with countless other substances within end products, every one with unique properties, some more and some less compatible with each other as far as swelling of plastic goes. Methyl hydrate (aka methanol, aka methyl alcohol) is an entirely different compound than ethanol. It will first make you blind, then kill you if you drink enough of it. Ethanol (aka ethyl alcohol, and not denatured ethanol, to which a toxin is added) is found in both "alcohol adulterated gasoline" and in whisky. Drinking whisky won't make you blind or kill you, but eventually, it can wreak considerable havoc on your health.

. . . .why isn't the the paint and decals coming off on your hands? The problem surely lies with proper tank placement or previous damage to the triple tree stops.

A tiny fraction of a percent of expansion over 10 years (in the case of my own fuel tank) hasn't been enough to damage either paint or decals. I reckon no one knows yet if that point will ever be reached, but I recall "infant mortality" for a couple years on some batches of tanks that blistered.

[raz]

Just undo your tank-suck fixes and it will shrink again

[Steve G.]

Both "plastic" and "alcohol" are very large categories of often complex compounds, of which there are literally countless entirely unique varieties and mixable combinations of each with countless other substances within end products, every one with unique properties, some more and some less compatible with each other as far as swelling of plastic goes. Methyl hydrate (aka methanol, aka methyl alcohol) is an entirely different compound than ethanol. It will first make you blind, then kill you if you drink enough of it. Ethanol (aka ethyl alcohol, and not denatured ethanol, to which a toxin is added) is found in both "alcohol adulterated gasoline" and in whisky. Drinking whisky won't make you blind or kill you, but eventually, it can wreak considerable havoc on your health.

 

A tiny fraction of a percent of expansion over 10 years (in the case of my own fuel tank) hasn't been enough to damage either paint or decals. I reckon no one knows yet if that point will ever be reached?

 

 

Thanks for the chemical description of the different alcohols available Ratchet. But my point is, Moto Guzzi and every other vehicle maker out there has had to use mandated tested "materials" that meet certain requirements, one being the specific " material " [don't want to confuse anyone about plastic vs vinyl vs Methyl alcohol vs Ethyl alcohol] made to make "fuel" tanks. Alcohol blended fuels were certainly available in most areas way before the 1999 V11 Sport was made, even before it was designed, even before it was prototyped. Clearly they would not have been issued Euro safety clearance or US DOT status if not using specific "materials".

You mention fractions of a percent expansion over 10 yrs. I put to you that simple heat expansion of said tank material causes more than fractions of a percent expansion, never mind what the tank is holding.

And when I talk of paint coming off the outside of the tank, I'm not talking of the tank expanding enough to separate the paint bond from the surface, I'm saying that if, using your chain of thought, the volatile fuel in the tank has compromized the tank material to an extent that it's causing it to expand, clearly it will also leach through the tank material very quickly in it's life, compromising the paint bond 'chemically' rather than 'physically'.

I've owned a GSPD beemer, with 9 gallon tank, they've used them since the late 1980's, no issues with paint, decals, etc, made by Acerbis just like the MG V11 tanks.

Steve