by KE4AVB » Mon Nov 09, 2015 9:57 am
This is normal; although, a leaky main nozzle or welch plug can make it excessive. What happening air is being drawn in pass the mixture screws through the ports in the venturi. I have seen few leaky main nozzles but those carburetors would not even pull fuel in from the tank because of this. I had a C1Q on a Stihl last month that would not prime. What I found was the welch plug over the main nozzle was completely missing allowing too air much to drawn in from the mixture ports as it bypass the mixture screws. Had to replace the whole carburetor because someone had already had the carburetor apart and lost the old welch plug.
If your engine runs fine then there is nothing to worry about.
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