Filling plastic tanks

[brent j]

I've just picked up a PE400T. The tank is in good shape from the outside but it's dry. I have no idea of how long it's been empty.

Is there any thing to do before I fill it up?

I plan to half fill it and leave it for a few days at least and see what happens

[80-85 husky]

pe tanks can split apparently so good plan. the tap may leak as well

[PEZBerq]

Not sure what half filling achieves? I would be concerned about uneven absorption of fuel or uneven drying out. A complete fill would be better surely ?

[80-85 husky]

not so much spills with half a tank

[geoff]

Hi....
I had the same problem with a PE 250 tank which had been left empty for years, filled it up with cheap engine oil and stood it for a couple of weeks, then emptied the tank and filled up with two stroke mix at 30.1. No problems.!

I had the same trouble with an empty tank not too long back and just filled it and within a couple of hours it split along the top level of the fuel. You live and learn!!

[Oldfart]

Brent ... they split on the bottom seam. Fill it up and see what happens.

[tymes]

Geoff might be onto something with that idea. I found once with a TT 350 tank that i had half full for a while then i filled it up and it split. I think if you fill and leave it a little while then empty it an do that a few times it might have time to absorb and swell slowly.  I have had some that have got like crazy craking on the outside sfter they were full for a while as well. Old tanks can be a fickle bit@h.

[frostype400]

I'd say most important make sure the vent works some times the cap blocks and wont vent and that will cause an issue also some people may over tighten the tank where the bolt goes through at the front down low and that can bow the tank inwards its important to check that the brackets don't have to come in before you put the bolt through if they do get a longer bolt don't force it in it puts pressure on the tank.

[Mike52]

Wish this had been posted last week.

[skypig]

I never considered any of this!

[kdx Geoff]

I've got plenty of Australian kdx tanks and have put fuel into old tanks (including one that had been empty for maybe 15 years) with no ill effects.

The pic is of a kdx450 tank that l bought from the UK, l don't know how long it'd been without fuel.
After many hours of polishing, l fuelled the bike and thought nothing more of it because I'd only seen PE and IT tanks fail through splitting etc and had never had an issue with a green tank..

After a couple of weeks of having fuel in it, over a 24 hour period the sides of the tank became concave (as in flexed inward) and began to separate and open up the seam.
I flushed the tank out with hot soapy water, lots of hot soapy water and over a couple of days it all went back into shape with the cracks and crazing closing up.

Very suspicious of old US kdx tanks now and wouldn't use this one for fuel.

[Mick D]

I think UV(Light) is the greatest cause of plastic degradation.
Look at the Plastic side of the bike that is stored leaning toward the sun.
Usually the only plastic item that still looks less "Chalked-Up",but still is on the sun side is to a lesser degree is the tank. So Fuel oil must be some sort of Saviour.

Frostype400"s post about not stressing a tank out when mounting it, makes more sense than anything I have heard for a while.

And Geoff,,,,

After a couple of weeks of having fuel in it, over a 24 hour period the sides of the tank became concave (as in flexed inward) and began to separate and open up the seam.

Thanks for sharing your observation with us,,,,
If the tank went concave? It is because the inside of the tank wall "grew" "expanded when wet again.
It may be reasonable to "assume" that a more realistic approach maybe to "immerse" or soak the whole tank in a "vat" so that the inside and outside can expand(and soak up) at the same rate. Maybe pulling it in and out of that "solution" over a period of days weeks or months to give the Tank a chance to normalise slowy,,,rather than Shock and Ore?

I truly believe the best way to store a plastic bike is to keep covers on them(UV protectors).
 
If the outside sunk and went concave, well then,,,that's a valuable shared observation 
 

[Mick D]

It would obviously be an expensive one off exercise to create a mould for a rare bike,,,,but "matcho mick" on here could easily use that cracked up sample to make a replica replacement out of fiberglass for that 450 Geoff.

[Mike52]

Russell the clutch cover maker could and has cast a Kawasaki one out of aluminum.
Came up pretty good.

[brent j]

I put in about 5L of fuel. A leak started from what looks like a repair on the underside about 30mm from the back.

I'll dry it out and see what can be done. No leaks from the seams.