Perhaps 30 year ago i read an article in a journal; 'Bacteria ate my car park', and it seemed a bit far fetched at the time. Knowing enough about that now to be dangerous, it would have been 'Sulphite Reducing Clostridia' attacking concrete: 'concrete cancer' i believe they call it. Seems that bacteria have eaten my carburettors
Having a read round it looks like the family Acetobacteraceae ferment sugars or alcohols and produce Acetic acid during fermentation which is highly corrosive to soft metals; lead, zinc, aluminium, and brass. The corrosive attack on the latter probably explains the bright green colour and looking at the jets and brass parts it easy to see they have been nibbled severely.
Having some of that green stuff on my fingers draining the bowls and picking up a small plastic handled screwdriver to have a scratch about in the drain plug, it was alarming to find the handle dissolving in my grip.
They are a universally occuring species which are usually found disolving alcohols and sugars in most plants. Ethanol mixed with oxygen in the air generates agressive by products in its own right and there are two different types of bacteria; aerobic and an-aerobic forms which can reduce ethanol so it can also be done in the absence of oxygen as well.
Taken together, with the presence of water, Ethanol being Hygroscopic, and leaving them un-attended in the presence of soft metals is a recipe for disaster.
My error was to run the bowls down leaving approx the comparative amount you see in the glass (second pic) which would have attracted water from the air to it, when i should have just drained out that last little bit.
The small amount left in each bowl / drain plug would have had the main jets and needle jets dangling in it and thats where the corrosive effects can be seen most clearly and my guess is that it was pulling air / water from the surrounding carb body down the needle jet hence the biofilm on the jet needles.
I will get some Aspen 4 and in the mean time drain the bowls completely between use if laid up until i can use the alkylate petrol for down time.
AL
https://link.springer.com/article/10.10 ... 015-6729-4
