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 Posted: 12-20-2018 06:26 pm
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 460
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There should be two gaskets in the choke (aka, enrichment device). One internal to the choke itself, and one between the choke and the carb body. Rebuild kits only supply the one that is internal to the choke. The other one needs to be ordered separately.

If the gasket between the choke and body is omitted during assembly, then fuel can leak out there.

Also note that it's easy to assemble the 'choke' incorrectly by installing the choke disc 180 degrees off (flipped over), in which case it may leak fuel. In addition, the choke may either not function, or never shut off. In the former case the engine will be hard to start when cold. In the latter case, the mixture will be excessively rich mixture at all times. This is another possible cause of excess carbon in the exhaust.

A compression spring slips over the Cold Start spindle (along with the special U-shaped circlip that snaps into the groove in the shaft) and forces the moving disk tightly against the fixed mating surface. That forms a sliding 'face seal', much like a water pump seal. Without the spring, the sliding joint could be loose enough to allow for a fuel leak. Even with the spring, if the sliding surfaces are corroded or otherwise rough or nicked, they won’t form a seal.

Regards,
Tim Engel

Last edited on 12-20-2018 06:33 pm by Esprit2