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Thread: Electrical problem

  1. #1
    Senior Member Wheels's Avatar
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    Default Electrical problem

    I started this thread a while back with this statement, but it became a discussion about heat dissipation. a worthy subject but ... I'm still down.
    "My 80HP 912 Rotax had a mag check failure at run up.
    First mag drop was almost nill, second mag was an erratic and rough running engine. Classic symptom of a module failure. I pulled the 4pin connectors and swapped them, no change. I pulled the ignition leads from the panel and swapped them and was able to swap the failure from mag 2 to mag 1. So I thought I had isolated the problem to the ignition wire from the panel/mag switch.
    Figured this was the problem so I ran a new wire and bullet connector from the connection, test was negative. Did the same for the other bullet connector and still having the same issue. I did a continuity test on the switches and both checked out. "Then ...

    I ordered another CDI (700.00) and while putting it in realized the state of the electrical system at the engine compartment was a mess.

    the bullet connectors that connect ignition and modules for the Rotax side of things are not something you can buy at NAPA. After much searching and phone calling to avionics and aviation supply houses, I learned that the connector is a motorcycle part. I am discussing the purchase of some bullet connectors with a vintage motorcycle parts supplier on line. Anyone ever see this problem before? I'm going to put new bullet connectors on the ignition wires from the switch and the red wires coming out of the engine. I bought a ratcheting crimper but I will need to peel back some of the metal braid at the wires coming from the motor. the photos are of the bullet connectors. They are hard to find. What have you done?
    thanks. When I have fixed this, I will put on a new ROTAX oil filter to see if that stops the oil from the pipe problem. Different thread.
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  2. #2
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    Default Re: Electrical problem

    I have bullet connectors on several vintage bikes. In short - I hate them - notorious for poor connection and come loose easily with heat/cool cycles. No one I know of uses them currently for the above reasons.

    I'd replace them all with Seal-Alls. You'll need the shells and pin/sockets or a kit. Try Aircraft Spruce.

    Greg

  3. #3
    Senior Member Wheels's Avatar
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    Default Re: Electrical problem

    The connections on the CDI are factory. Changing them to "seal all" doesn't appear to be an option. The web site shows a completely different configuration.
    So really I need the source for the CDI terminal connections shown in the photo. Has anyone ever had to repair the opposite side of the CDI wiring?

  4. #4
    Senior Member jmodguy's Avatar
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    Default Re: Electrical problem

    I have been working aircraft electrical and avionics systems for 30+ years. I currently work for a major defense contractor in the wiring and interconnect dept. I will say this about bullet connectors. They are JUNK.
    I cannot believe these are being used on an aircraft engine, let alone something as critical as an ignition module.
    We spend 10s of thousands on an airframe. 10s of thousands on an engine and we always go cheap on electrical connections and wire and wonder why they don't last.
    Change them out to a machined contact. You can get mil spec connectors (38999 Series III) for your 10s of thousands of dollars aircraft for a couple hundred from Mouser, DigiKey or any of the other big parts suppliers.
    Let me know what you need and I can help you find the right connector.
    Jeff
    KF 5
    340KF

  5. #5
    Senior Member Wheels's Avatar
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    Default Re: Electrical problem

    here is the picture.
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  6. #6
    Senior Member Wheels's Avatar
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    Default Re: Electrical problem

    So I just got the picture to work. Are you saying that these connectors are not good for the rotax engine? Am I not using the right terminology? Isn't that a bullet connector? It's stock and the wires on the module are too short to modify by cutting off the old connector and adding anything else. So these are the connectors I am looking for unless there is a way change them. Am I wrong.
    I need to fix this mess and fly this motor before it goes up for sale but if I can't fix it then it becomes a 'parts' engine or a non working rotax 912. Seems like a shame for a motor with only 700 hours on it. In the 16 years since manufacture am I the only guy to have this problem?

  7. #7
    Senior Member jtpitkin06's Avatar
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    Default Re: Electrical problem

    Yes, they are called bullet connectors. Do a search for "DigiKey Bullet connectors" or "Mouser Bullet Connectors". Either company can supply you with hundreds of styles and sizes of connectors.

    Both are fast shipping and have no minimum. I've ordered a 50 cent part from Mouser and had it the next day.

    John P

  8. #8
    Senior Member jmodguy's Avatar
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    Default Re: Electrical problem

    Wheels,
    Thanks for the pic. I can understand now why so many people are having problems with these modules. Bullet connectors and PVC jacketed wire. I'm guessing the wire (under the jacket) is standard hardware store grade stranded wire.
    Bullet connectors are not good for ANY aircraft engine.
    If you can replace them and get the engine running, by all means do so! Then sell it!
    I will not use anything other than Tefzel jacketed wire on an engine or in an engine compartment!
    Jeff
    KF 5
    340KF

  9. #9
    Senior Member Wheels's Avatar
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    Default Re: Electrical problem

    thanks for the replies and the info for sourcing. I know the Rotax 912 has millions of hours on it with this system but it is worn out considering the technology available today. I'll replace with like items and stay "stock" per factory standards and put the engine back in service. I will fly it for a while before selling it as I have a new one waiting in the box for my completion of the refurbishment of my little ship.
    Thanks again.

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