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3W 80 XI

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Old 08-21-2011, 12:47 PM
  #1
soinks
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Default 3W 80 XI

I hope someone can help with a problem I have with a 3W 80 XI. Last season it ran perfect this year it won't idle down when coming in for landing. I adjusted both the low and high speed needles that didn't help and checked the throttle servo. I wonder if gas with ethanol has done something to cause this. I'll appreciate any feed back that I get and thanks for your time.
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Old 08-21-2011, 01:07 PM
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Tired Old Man
 
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Default RE: 3W 80 XI

Typically a problem with a slow idle down eminates from an excessively lean low needle. It can also be caused by the engine sucking air somewhere around the induction tract. You have had etahnol in your gas for some time now so I doubt that to be the cause. Worst case you had the diaphragms in the carb wear out which can be resolved by picking up a $10.00 carb rebuild kit and replacing them. A 20 or 30 minute job.

So first thing I would do is adjust the low needle a little richer. Since you stated you had adjusted both needles it makes me think that's where the problem started. If that doesn't work I would try having the engine running while I sprayed some WD-40 around the base of the carb to see how the engine reacts. If you're not spraying into the carb, and only onto the base of the carb, changes in RPM would indicate a likely air leak that needs corrected. Normally those are also easy to fix with either a simple re-surfacing of the plastic insulator riser or installing new gaskets.

While I was doing all the above I would take the time to go through the plumbing to check for leaks or line splits from the carb all the way back to inside the tank where the tubing connects to the pick up line and clunk.
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