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Ignition Circuit -B- Problems

in 912 / 914 Technical Questions 7 years ago

  • Re: Ignition Circuit -B- Problems

    by » 7 years ago

    Hello Tom

    Congratulations! I tested the gap a couple of months ago but not very thorougly. I will do it again.

    3 Questions:

    - Did you use a feeler gauge for the procedure?
    - Did you mean Milimeters or inches when you described the gap?
    - And: -HOW- did you modify the gap? The Manual says the the gap is hardly adjustable. Any Pictures you can post?

    All the best

    Gerhard
      
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  • Re: Ignition Circuit -B- Problems

    by » 7 years ago

    Hi Tom,

    Glad it worked out. Time to go have fun now. :)


    p.s.
    For those that need to adjust the trigger coil gaps it is better to set it at the narrow gap setting limit vs the widest gap setting.

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

      
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  • Re: Ignition Circuit -B- Problems

    by » 7 years ago

    Gerhard,

    Here's a few answers to your questions ~ Yes, I used feeler gauges to set the gap. I have an older 912UL engine with the 'older style' trigger coils that are discussed and/or shown in the maintenance manuals online. That basically means they are not slotted, just a slightly oblong/open mounting hole. After having adjusted my coils, I can see why they now make them slotted for more adjustment allowance. I used steel, flat feeler gauges and set the coils for 16 thousandths (aka .016 decimal or 40 mm).

    You loosen the #4 allen screw/bolt that holds the coil to the back of the engine case so you can make adjustments. Because I have the older style coils, they limit the amount of movement/adjustment I could make. Fortunately, that was enough to obtain the required gap I needed. I did have to hold pressure on the coil while tightening it down so it wouldn't move out of gap.

    Sorry no photos but you can glean most of this info, including pictures, from the manuals. I found my info on Rotax-Owner.com under the 'engine manuals' tab. I don't have a black plastic cover on the back of my engine so accessing the stator and coils was pretty simple for me. I used a mirror and good lighting to see what I was doing, etc.

    Hope this helps AND that you'll get your ship running smooth soon! Huge thanks to Roger for the 'tip/steer' to check those coils!

    Regards,
    Tom

    cil
      
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  • Re: Ignition Circuit -B- Problems

    by » 7 years ago

    Hi everyone,
    I've been having struggling with a similar issue. Ignition check produces a 350 rpm drop on the B circuit and engine running rougher than normal above approx 3000. As with everyone else troubleshooting isolated problem to B circuit and ruled out modules, wiring, plugs. I checked the pickups last night and found B3/4 to be on the high end .016 and the rest at .012. I set B3/4 to .012. and the engine runs smoother than ever at idle. However no change in rpm drop or engine roughness. I plan to double check pickups as soon as possible. I m wondering if the pickups may have moved slightly causing a timing issue?
    Any thoughts, advice would be appreciated.
    I'm current l looking for a timing light to run timing checks in the manual.

    THANKS
    Mike
      
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  • Re: Ignition Circuit -B- Problems

    by » 7 years ago

    Dear companions in misfortune

    Today I finally found time to verify the gaps. As expected one of the -B- triggercoils (B1/2) showed an opening of slightly more than 0,50 Millimeter (0,196 inches) s. Picture below (arrow)

    What, technically speaking, happens to the ignition if the gap is exceeded? Spark becomes weaker and/or timing shifts behind -A- ? Up to complete spark-failure?

    As I noticed the trigger coil shares one lifting point (Allen screw) with the adjacent -A- Coil !
    Do I have to loosen this one also in order to fix the -B- gap? I´m afraid to mess up the healthy A-neighbour while doing this....



    Greetings from Stuttgart/Germany

    Gerhard
    230620171607.jpg (You do not have access to download this file.)
      
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