Rotax 80hp, ignition problems

[JorgeEC-YUQ]

and here the video I took of my spark plug ...

https://www.youtube.com/watch?v=0s61h6TgHYE

Jorge

[Av8r3400]

The insulation on the stator getting "gummy" is the reason for Rotax's stator SB calling for its replacement. I don't know if other changes were made internally or not. I would have suggested that if you had it apart that far, not to repair your stator but replace it with the updated unit.

These shorts in the wires may have already damaged your new (?) CDI boxes.

Have you already put it all back together?

The spark looks normal other than it may not be hitting every time.

Note: never try to operate these ignitions without spark plugs or with the plugs insufficiently grounded to "check" the spark. This can and will damage the CDI boxes.

[JorgeEC-YUQ]

I put it all back together already ...

Yeap, looking back would have been clever to replace the stator but I didn't had any.
My local distributor would sell the full assembly, not only the stator, (with the new style connectors, so installation apart) for +1200 euros.
That without knowing for sure it would be the cause. Providing that this SB was referring, as you say, to the cable quality and that the stator, being so simple, would be operational it was my main motivation to try to fix my one ... that and the thousand bucks.

But maybe it would have been worthy indeed ...

Do you think this is the right track ? Is the spark is missing due to the CDI's being broken?

But I still don't understand ... could that mean the engine was always running on 3 cylinders and this is why the ignition test was somehow OK ??

My next plan is to swoop the full ignition from the 100 hp ... If that doesn't fix it this engine has to go.

Thanks for the note, good to know one shouldn't play with the spark plugs ... live and learn as they say!

Thanks for your responses,
Jorge

[Wheels]

I fought an engine vibration for months until a friend showed me a small crack at the top joint by the rubber isolation dampner.
I thought it was just cracked paint, but when I removed the engine, the crack became very visible. there were actually two? Kit fox came out with a more robust engine mount several years ago. It may be worth your time to use a magnifying glass and inspect every part of that mount, with the engine mounted is fine.
My favorite engine mechanic missed it for 18 months. I replaced the broken mount and the vibration was gone.

[JorgeEC-YUQ]

woow ... scary one!

I checked the engine mount looking for cracks before I repaint it when I had the engine off the plane... but I will re-check again after seeing your pics.

I found something interesting yesterday in other forum. About an old rotax engine (like mine, 12 years) having lost some of its magnetic properties on the stator. Due to age and heat? They call it lazy stator ...

You can find it here: http://www.recreationalflying.com/th...roblems.10397/

Any thoughts?

Jorge



Thanks for sharing!






Jorge

[Av8r_Sed]

I wouldn't put much stock in the "lazy stator" theory. It's basically iron laminations with wire coils around it. If the coils are connected and there's no short in the insulation, you will achieve strong magnetic fields. In other words, it will work or not but shouldn't slowly die.

[Paul Z]

Checking the Resistance should have caught that problem.