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Hi All,

Food for thought and a quick tip to make maint. and flying better.

During the annual you are supposed to remove the float bowls and look for debris and weigh the floats. It's on the maint. checklist. Since you are into this this far you might as well take 5 minutes and remove and clean the idle jet. I just push the carb back out of its rubber socket so I can tilt the bottom towards me and raise it up a couple of inches to clear the heat shield / drip tray. 

So while the bowl is off you can take a flat tip screwdriver and unscrew the idle jet located right next to the brass protruding main jet. I find most at least half clogged and some fully clogged. If you hold the jet up to the sunlight you should see a small clean hole through the center of the jet. Most times you can barely see it or not at all. This causes harder starts. Take a 8" piece of #14-18 gauge wire and strip back about 5" of the insulation. Unwind just one strand . This is how tiny the hole through the center of the idle jet is. DO NOT use a drill bit or anything else along this line. This will damage the jet hole, but the wire will not. I've been doing it like this for almost 20 years and never had an issue.  Put the single strand of wire through the center of the idle jet and slide it back and forth and twist it in circles. This will break up any debris and dried fuel. Then follow up with some spray carb cleaner like "Brake Clean" with the 6" long red nozzle. It's small and fits inside the jet for a good flushing down through both ends of the jet. Now follow that with some high pressure air. Now that this is done look through the idle jet again against the light and you should see a small, but nice clean passage through the center of the idle jet. Now just screw it back in place and replace the bowl and floats. Owners that don't seem have have easy starts can do this anytime. If someone has a really high unequal vacuum on their gauges on one carb at idle during a carb sync you can have the same issue with the idle jet and may need cleaning. 

This is easy and quick to do while the bowl is off so you might as well do the next best thing and be that cut above average.


Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell

  • Re: Tip of the day-The idle Jet

    by » 2 weeks ago


    That's what I'd call idle talk...  😆


  • Re: Tip of the day-The idle Jet

    by » 2 weeks ago


    Your tip is most excellent!

    As a caution, since I discovered this problem on my ship, be careful when removing the float bowl. The guide rods for the floats stick out above the level of the bowl and the drip tray or other obstructions often exist beneath the mounted carb. If one does not lower the bowl sufficiently before removing it sideways, the pins can hook something and a ham-handed pull can bend one or both of them. A bent pin can cause the float to stick against the side and prevent its free vertical motion. One can see this in a picture of a bowl upon its first removal under my ownership. This situation will mess up the fuel level and cause problems if not corrected.

                           


  • Re: Tip of the day-The idle Jet

    by » 2 weeks ago


    Roger,

    Sounds like a great idea, however I am concerned about one thing: in order to push the carb out of the socket and twist it 90 degrees, wouldn't you have to disturb the throttle and choke cables enough that it would require you to resync the carbs pneumatically and maybe even mechanically? I always check the sync at annual with the gauges, but many times don't need to readjust anything. I am afraid your suggestion would force a complete resync every annual, a lot more work.


  • Re: Tip of the day-The idle Jet

    by » 2 weeks ago


    It doesn't affect the choke or throttle cables. They have enough play to not be an issue. You push it backwards  about an inch to clear the rubber mount which gives it even more play. Then you tilt the bottom outward and raise it up about 1.5" to to clear the drip tray. Been doing it this way on all LSA and have never had an issue. It will not affect the throttle settings. If you didn't do this how would you remove the bowl for the regular inspection.

     

    p.s.

    I do loosen the airbox rubber collar if that engine uses the Rotax airbox and occasionally I have to remove a K&N air filter if there is no room between the end of the K&N and the firewall, but that's not common. I loosen the airbox rubber collar so the carb can tilt and move freely.

     


    Roger Lee
    LSRM-A & Rotax Instructor & Rotax IRC
    Tucson, AZ Ryan Airfield (KRYN)
    520-349-7056 Cell


    Thank you said by: RotaxOwner Admin

  • Re: Tip of the day-The idle Jet

    by » 2 weeks ago


    Roger, that was an awesome Tip because it is not talked about enough and a real on going issue. I check mine at least once a year, Thanks again for the thought.


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