I think my carburetor is really in trouble-pitted

It all started with the following symptoms: Moped would die when you put the accelerator in the middle range, especially right after starting. Then the moped started dying after riding it for a little while. It acted like it ran out of gas. Not sure if the two symptoms are connected

We drained the tank. (tank is in good shape) cleaned the fuel lines and the petcock. The problem still persisted and maybe got worse. I also had put in carburetor cleaner somewhere along the line. Now gas has started dripping from the carburetor!

So now I've taken the carburetor out. Parts of it are pitted as if someone had soaked it in acid! A previous owner had epoxied the float tank, so this isn't a new problem.

The carb seems to be made of some kind of cast alloy. My dad thinks that it was designed before unleaded fuel was common (1978 Vespa Bravo) and the unleaded fuel (which contains methyl alcohol) corrodes the alloy. However, I've never seen anyone mention anything in this forum about not being able to use unleaded gas, is this really a problem with older mopeds?

Re: I think my carburetor is really in trouble-pit

Not all unleaded contains methyl alchohol, one of the big things they use in it is ethanol, and if you check I'm pretty sure leaded gas was readily availible in 78.

Did you check the petcock to make sure there is good flow from it? What kind of carb cleaner did you use and where did you put it?

Soaking in acid seems to me to be a common occurance with some morons working on bikes, I had a carb that was eaten all the way through by an acid bath.

Re: I think my carburetor is really in trouble-pit

Carbs are die cast from a low melting point zinc alloy with some tin, lead, etc... commonly known as white metal or pot metal.. pretty much immune to alcohols and common fuels and that's why it is used for carburetors.

All metals and alloys oxidize and corrode to some degree just by sitting around. Since someone had problems with that carb, whatever method or chemicals they used to clean it may have had something to do with the corrosion.

Commercial carb cleaner is a powerful combination of solvents.. and sometimes that's the last straw for an old dried-up gasket or 0-ring.. A little carb cleaner is recommend to _keep a carb clean_ after it has already been thoroughly overhauled, but there is no substitute or shortcut for a proper carburetor cleaning and examination, especially with a new(old) bike..

After repairing any leaky gaskets or whatever, I would start with the obvious.. the "repaired" float.

If a float is damaged or not working properly, the effect on performance can be a variety of things, including the running-out-of gas symptom.

Re: I think my carburetor is really in trouble-pit

oops.. i misread that.. You say the float "Tank" was epoxied? I'm gonna guess this means the float bowl itself was epoxied?

If i got that right, it sounds like it was cracked or was, more likely perforated by the corrosion.. and that does point to something unusual, like the carb parts were put into a hot-tank or something similar that partially dissolved them.

the fix seems to be, after removing all the old stuff, more epoxy.. Or a new bowl.. Or a new carb, since there may be corrosion problems that you can't see..

Re: I think my carburetor is really in trouble-pit

Angelo Massimino /

I don't know what could be happened to your carb: I believe it and its gaskets have been destroyed from the cleaner you have used.

What I whish to tell you here is just this: if you need, I could sell you an excellent used carb in excellent working order.

If you take interest, please reply by e-mail

Re: I think my carburetor is really in trouble-pit

Maria, it sounds like debris in the main jet or emulsion tube.

ALSO replace the spark plug every time to make sure it isn't carbon-tracking and therefore misfiring.

Completely clean the carb or replace it. don-ohio

Re: I think my carburetor is really in trouble-pit

well i have a bing carb ill sell it to you for $30

all is needs is a flote bowl gasket and a return spring

email me @ moody07747@yahoo.com

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