Shrinking a swollen petrol tank

Dukesox

Dukesox

Elite Member
Subscriber
The plastic tank on my Monster has swollen a little over the last couple of years and this Winter I plan to try to shrink it back to original size if I can. I`ve read various suggestions on the best way to do this with the top 3 being :-

Drain the fuel , leave the tank in place with the fuel cap open.
Remove the tank and keep in a warm place for several weeks .
Remove the tank and keep in a cold place for several weeks.

Do any of you have first hand successful experience with shrinking a swollen tank and if so what did you do ?

TIA
 
Not sure if the Aprilia tanks were similar but on my little rs250 the tank had swollen which was common in those bikes so I drained the tank left it over winter in the roof of my garage cool and dry and it shrank back a little bit which was just enough so the clipons weren't hitting the tank..
 
Righty ho, tank now is just attached to the bike at the frame where the saddle sits. Pump and petrol flap both removed and I have 3 questions :-

Is there any reason why I can`t leave it as is or should I take it off entirely ?
Its in the barn so while wind and water tight it isn`t heated so will be cold over the Winter. Is that the best way to shrink it or would putting it in the airing cupboard be better as much warmer?
@Markduc suggested blowing air through the tank, again with regard to temperature , which is better, hot or cold ?

TIA

1698058433810.png
 
I think my tank was left in the garage with the fuel filler open and fuel pump/flange assy removed.
 
The whole bike was then moved into the house sometime after that.....I'm afraid I can't remember exact timings.
 
Dukesox said:
Righty ho, tank now is just attached to the bike at the frame where the saddle sits. Pump and petrol flap both removed and I have 3 questions :-

Is there any reason why I can`t leave it as is or should I take it off entirely ?
Its in the barn so while wind and water tight it isn`t heated so will be cold over the Winter. Is that the best way to shrink it or would putting it in the airing cupboard be better as much warmer?
@Markduc suggested blowing air through the tank, again with regard to temperature , which is better, hot or cold ?

TIA

View attachment 88395
Click to expand...
Maybe a computer fan could be rigged up to blow air through, apparently it’s moisture from ethanol fuel that gets in the pores of the tank so any air flow should help, I wonder if those dehumidifier crystals would help
but if you have ethanol in your fuel it’s only going to do the same all over again
my tank is slowly shrinking back after a couple of years with no ethanol
 
Yeah ,...the sad fact is it will grow back when back in use...that is with e5. Can't imagine how bad it'd would be with E10. I think mine was liveable. As Mr Marcduc says it's the moisture being absorbed into the plastic making the tank swell. What happens is the ethanol in the fuel absorbs water this water/ethanol mix then separates out from the fuel ...I believe this ethanol water mix is quite nasty to some metals .. plastic and rubber....as well as the water being absorbed into the tank plastic

If you do some searching on the UK Monster forum you'll find plenty of good info....some of which I was contributing to.

Some folk speak of a chemical additive which stops this separation happening ....(phase separation) ...I have the motorex version which I put in the multistroodle over winter if I have some fuel in the tank...I really have no idea if it's prevented any of the gubbins from being damaged inside the tank.
 
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Ger said:
Yeah ,...the sad fact is it will grow back when back in use...that is with e5. Can't imagine how bad it'd would be with E10. I think mine was liveable. As Mr Marcduc says it's the moisture being absorbed into the plastic making the tank swell. What happens is the ethanol in the fuel absorbs water this water/ethanol mix then separates out from the fuel ...I believe this ethanol water mix is quite nasty to some metals .. plastic and rubber....as well as the water being absorbed into the tank plastic

If you do some searching on the UK Monster forum you'll find plenty of good info....some of which I was contributing to.

Some folk speak of a chemical additive which stops this separation happening ....(phase separation) ...I have the motorex version which I put in the multistroodle over winter if I have some fuel in the tank...I really have no idea if it's prevented any of the gubbins from being damaged inside the tank.
Click to expand...
I`ve had the bike about 4.5 years now but the swelling started this year after I had run very low on fuel and only E10 was available at the filling station I had to use. I filled up and this petrol stayed in the tank for perhaps 7-10 days. I`d never had an issue using E5 so I am guessing that the one off use of E10 was the problem and hope that if I can shrink the tank and avoid E10 in future it will stay shrunk. With the benefit of hindsight I should have just put in enough E10 to get me home and then drained the tank.
The updated plan for the winter is to get the tank off the bike and into the airing cupboard and additionally I`ll blast it internally with hot air from the Trouble`s hairdryer periodically . I`ll look into absorption crystals and tank liners over the winter too.
 
I wonder if you were getting some expansion (avoiding the "s" word as it'll soon attract attention) 😄 before you used the E10 but hadn't noticed it:unsure:..

How is the expansion showing ?....the rubber buffers overhanging frame rails? .....the catch getting very close to the ignition? ..... because pushing the tank back and adjusting the buffers position might help.
 
Ger said:
I wonder if you were getting some expansion (avoiding the "s" word as it'll soon attract attention) 😄 before you used the E10 but hadn't noticed it:unsure:..

How is the expansion showing ?....the rubber buffers overhanging frame rails? .....the catch getting very close to the ignition? ..... because pushing the tank back and adjusting the buffers position might help.
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Ooh er matron.
You may be right and I had not previously noticed anything . So far it appears to be showing mainly in the length as the front is now very close to the ignition. If no shrinkage occurs then I`ll look at pushing the tank back a bit with a bracket similar to the one you showed in post 14.
 
When I made my bracket I used a short length of box section aluminium bought off eBay .... It was a few mm wider than original bracket ....but I used some plastic washers to shim up the difference....and a longer pin ....also bought off eBay ..

The wider bracket with the plastic shims is a better solution than the original in my opinion as it protects the plastic tank from damage when lifting the tank up. My tank was scored and damaged around that pivot point.

I think I may have some of those longer pins kicking around ...clevis pin IIRC :unsure:
 
Dukesox said:
I`ve had the bike about 4.5 years now but the swelling started this year after I had run very low on fuel and only E10 was available at the filling station I had to use. I filled up and this petrol stayed in the tank for perhaps 7-10 days. I`d never had an issue using E5 so I am guessing that the one off use of E10 was the problem and hope that if I can shrink the tank and avoid E10 in future it will stay shrunk. With the benefit of hindsight I should have just put in enough E10 to get me home and then drained the tank.
The updated plan for the winter is to get the tank off the bike and into the airing cupboard and additionally I`ll blast it internally with hot air from the Trouble`s hairdryer periodically . I`ll look into absorption crystals and tank liners over the winter too.
Click to expand...

When we were in Ireland there is very little E5 available so had to use E10 most of the time, and no issues with it.

Mind, it's a metal tank.

As you were.
 
Dox said:
When we were in Ireland there is very little E5 available so had to use E10 most of the time, and no issues with it.

Mind, it's a metal tank.

As you were.
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IIRC there is a Monster owner on Mordor who had the same trouble as I am having , he decided on a bespoke brushed aluminium tank I think. It looked beautiful but cost somewhere close to £2Brazilian which is more than I`m comfortable spending on it.
I wonder if any of the steel tanks from earlier Monster models would fit - any idea anyone ?
 
Exi's mates over in CA used to market a glass fibre or summink replacement tank iirc ...
 
I actually have a new tank in its box tucked away ..., keeping it to offer to whoever I sell my S2R to ......when I can be arsed to recommission it .. so it's mint and could be coated inside (if that works).......
 
Ger said:
I actually have a new tank in its box tucked away ..., keeping it to offer to whoever I sell my S2R to ......when I can be arsed to recommission it .. so it's mint and could be coated inside (if that works).......
Click to expand...
Which S2R have you got , 800 or 1000 ?
 
It happens on the SF’s as well, I believe Rob had one replaced under warranty when he owned a SF1098S.
The one on my SF is fine at the moment, I use this additive as recommended by @HootOwl and never use E10.
motorex.com

ETHANOL TREATMENT

Fuel additive that improves the properties of all fuels mixed with ethanol. Its properties reduce phase separation/separation, optimise fuel efficiency and reduce corrosion. Ensures that the engine runs more easily, removes deposits in the combustion chamber, regenerates old fuel and helps to...
motorex.com motorex.com
 
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