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SJ .50 Carburetor Question

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Old 01-08-2009, 11:29 AM
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MikeyLikesIt!!
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Default SJ .50 Carburetor Question

Folks,

First, this is my first JETT engine and, accordingly, I have no previous experience with them. I have some familiarity with small model engines, however, which brings me to my question. My experience with previous engines has been that carburetor linkages moves smoothly forward from completely closed to completely open. On the .50 I received yesterday, the transition from fully open to about 75% closed is fairly smooth, but with the last 3/8" travel, it becomes significantly harder to close, as though you've hit some sort of stop and you're forcing it to travel that last 25% to close fully. Does this describe the normal and proper operation of the throttle linkage/barrel, or does it sound as though there is a problem?

Thanks for your response.

Mike Kelly
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Old 01-08-2009, 12:45 PM
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bob27s
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Default RE: SJ .50 Carburetor Question

Hi....

Thanks for writing....

The carb should function smoothly over the entire range.

Take a quick look in the carb and make sure a piece of debris/fuzz or something is not in there restricting movement.

Sometimes when the engine is new (and a bit dry yet) the carb barrel guide slot might hang up slightly on the guide screw as it closes. But that is rare. In general, the carbs are lapped fairly tightly and they do break in slightly during operation.

Adjusting the guide screw or screwing the low speed mixture inward can cause a premature hard stop at low throttle. Does not sound like that is the case here, but woth noting for others who may read the post.

Bob
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Old 01-08-2009, 06:22 PM
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Default RE: SJ .50 Carburetor Question

Thanks for the reply. Nope, nothing noticeable in the carb. I'm surprised, because I definitely would have thought that something as restrictive as this linkage operates would have been noticed during assembly. In any case, I guess it's back to the factory for this one...
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