How does one? I’ve a Moto Guzzi Norge with me at present and as I was going over the bike I noticed all these bubbles under the paint on the tank. Now the bike has been standing unused for a while, hence me giving it a once over, and I suspect these bubbles are caused by the effects of ethanol in the fuel and, at a microscopic level, a series of holes in the molecular structure of the plastic fuel tank. Would that be a correct assumption? Does anyone know? How best to get rid of them?
Looks like you're spot on. Not a lot you can do, I've heard conflicting stories. Dry the tank out and the plastic will shrink back and then you can coat the inside. Other horror stories are more along the lines of "it's scrap and needs be replaced..." sort :-( I feel for you. Must be heartbreaking.
It doesn't have to be ethanol, damp and moisture alone will have exactly the same effect. if you look through some old posts or do a Google search including "ducatiforum" you will see the subject has been done to death on here paul, - i won't waste time going into detail now though because an early spec M900 drain plug has just come to mind.
I think it's caused by damp, happened to a few of my bikes ( including a wrapped one) and also my vx220 ( fibre glass bodywork) on which it's known to be a common problem caused by osmosis
Osmosis of what? The fuel from inside the tank to the outside but underneath the paint or the osmosis of moisture in the air, through the paint and then getting trapped between the paint and plastic tank?
No, on the car it can't be fuel, might be coming outwards through the fibreglass bodywork and getting trapped below the gel coat ? Probably a red herring here, sorry, but it's the same end issue, bubbles in the paint, how do you get rid of them, osmosis is common on yachts but they sit in water a lot of the time.
Let me check the bike it's happened on, and see if it's just the tank, in which case it will be fuel only the one bike with plastic tank then. Also have a 1098r now, and it's not happened on that , different plastic? The other is an old 2004 monster
all the tanks made by Acerbis using PA6 are porous and will allow water through the material given time.
It's a common problem on bikes with plastic acerbis tanks. There was a class action suit against Ducati about 20 years ago. The plastic seems to absorb water from the fuel and swells. This is aggravated by higher ethanol levels in fuel as it is hydroscopic. People often discover it if the tank is stored with fuel off the bike during winter maintainqnce, drain it during this storage time otherwise you might not be able to refit it. If your tank swells you can dry it out and it will revert to shape, but it takes a long time, weeks or more.. Bubbles in the paint are not so easily fixed though.
As mentioned above it's micro blistering and is common where water or moisture eventually rises to the surface of the paint and then often blisters after a cold or freezing spell. It happened to my 998 over the winter and now I will need to repaint the tank when the warmer weather arrives.
Honda (for example) have used a different "plastic" material in the past which is unaffected dimensionally etc by water but overall not as good at impact survival re: fracture. PA6 performs incredibly in this area.
Didn't think to measure it first but the bolt wouldn't go in so I have a guage, I'll pop it back on the bike over the weekend and let you you know, think it was you who suggested drying it out so think you, it had definitely shrunk a bit when I last checked it
well it's Paul's thread Ivor! - that's the way it works - i have tagged my last post onto here:- https://www.ducatiforum.co.uk/threads/1198-tank-expansion.75915/page-2#post-2148335
I have seen this happen where modern water based paints haven't been oven dried sufficiently after painting. Small bubbles subsequently show up in the paint some time later.
