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Old 08-06-2022, 12:07 PM
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edwardc edwardc is offline
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An oscillating RPM is often caused by fine dirt in one of the jets. It momentarily leans the mix slightly as it passes through. Small amounts of water can do this too as a tiny droplet of water passes through.

The A4 is tolerant of a lot of things, but one thing it insists on is clean fuel.

The only way to insure this is start at one end (the tank) and systematically work your way to the other end (the carb), insuring that each step is clean before you move on. It does absolutely no good, for instance, to clean a carb, if the filters are overloaded and shedding fines downstream. Similarly, it does no lasting good to replace the filter(s) if the tank is harboring fines or water. 17 years is plenty of time to have accumulated "stuff" in the tank.

As for carb life, I've had mine running for 12 years, and the previous owner for 3 years before that. The only problem has been a defective float that filled up on one side and was easily replaceable. A full rebuild has never been necessary just an occasional cleaning.

When cleaning the carb, be sure to use a fine wire to ream out each of the orifices. Simply spraying "carb cleaner" through it isn't enough. The wire from the center of a bread tie is about the right size. You can also use a gas welder's tip cleaner wire.

Good luck and keep us posted!
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@(^.^)@ Ed
1977 Pearson P-323 "Dolce Vita"
with rebuilt Atomic-4

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