Getting rid of bubbles under the paint on a petrol tank.

West Cork Paul

West Cork Paul

Man in a Shed
Subscriber
How does one?

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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?
 
West Cork Paul said:
How does one?

View attachment 100881
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?
Click to expand...
It`s quite common on Guzzis of that era for bubbles to appear and yes it is down to the ethanol. I`m not aware of a cure.
 
West Cork Paul said:
How does one?

View attachment 100881
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?
Click to expand...
Not seen this Paul, my mate has two guzzi's, a 1200 sport and griso martini special both in black. I will check them when I see him in June.
 
BobTheBounder said:
Not seen this Paul, my mate has two guzzi's, a 1200 sport and griso martini special both in black. I will check them when I see him in June.
Click to expand...
I think it mainly affects the Norge and Breva models although I`m not sure why as both the Griso and 1200 Sport were produced around the same time. I`ve seen several Norges and Brevas with this problem but never a Griso or 1200 Sport.
 
The blistering is either caused by osmosis (solvents travelling through the substrate) or water molecules trapped under the paint.
If it’s a metal tank, I’d suggest it’s the latter, if it’s plastic it might be substrate porosity.
I presume plastic?
 
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