Ignition Gremlin

[Dusty]

Update
Problem found! My 912 was running better apart from a few stumbles on takeoff.
Witnesses on the ground were at odds as to whether it was a lean miss or flooding but definatly not developing power on two cylinders.
The floats and float levels had been replaced and checked multiple times,so I decided to replace the float needles (again) the fuel hoses and banjo fittings were removed and everything blown with compressed air.
On testing fuel ran out the r/h carb filter,the carb was stripped again,blown out and visually checked ,nothing visable.
A bit of wire was wiggled in the fuel intake side of the needle assembly and blown again.
An object was observed flying out the port! whatever it was, it wasnt getting blown out untill it got broken up.
Reasembled and test flown, consistant idle,smoother running no more stumbles!
I now have had around ten hours of trouble free flying.
I was dealing with at least two seperate issues which have been resolved and can now really start to enjoy relaxing flight
The moral of the story,NEVER ASSUME .
The carb had been stripped blown out multiple times with the debris still in place,perhaps a magnifying glass should have been used,or as been suggested, pressurise the fuel system and the fuel flow flow visually checked from the needle seat, an obstruction may shown up as an irregular flow pattern.
I hope this lesson may someday save someone else a lot of grief.

[DesertFox4]

Glad you persisted to discover the cause and the remedy.
I had a similar issue after both carbs were cleaned and rebuilt. I couldn't even sync them the right one was so bad.
Removed it, disassembled it and found a small piece in of debris lodged in one of the tiny journals. Reassembled, synced and it has run flawlessly for two years since.

[Dusty]

The story continues
My 912 was now running perfectly I had the plugs on my early modules changed to 6-4-1 ?
I was flying on borrowed modules which needed to be returned.
My original module A was fitted and around 15 hours all good.
The fun started when I replaced module B,mag drop was 50-100 rpm more than on A.
Test flight saw possible roughness on full power and when on cruise a random kick in the airframe ( literally like someone kicking the airframe).
The borrowed B module was refitted,all good again.
Question 1,do modules fail like this?(starting on this module alone was good and the wires appear good)
Question 2, I have been told there is aftermarket modules available that are around half the price of the originals that also have a live feed for starting and in case of a stater failure.Can anyone confirm this and were do I get them?

[HighWing]

Not sure this will be helpful, but years ago I rebuilt my carburetors and the engine started running rough especially at idle. This was especially noticable after a flight while idling at taxi with fuel spilling from the carburetors. I can't remember where the suggestion came from, but I switched back to the original float needles and smooth. I learned that Rotax makes several versions of the float needles to accommodate the different engines. The difference being different hardness in the rubber tip of the needle. Apparently the one supplied with the rebuild kit was the wrong one for my engine and it allowed fuel to leak during the normal engine vibration resulting in flooding.

[Av8r3400]

The proper tips for our planes are the red (soft) ones.

[Dusty]

I originally had the orange tip needles, our local rotax supplier only has the black tips,I use clear vent lines that usually stain with overflow there doesn't seem to be a problem The engine was running perfectly until I swapped to my original module. With the borrowed module back on all is good again
I am sure it is a randome module fault so would be happier with two new ones.

[Av8r3400]

Dusty,

I wish you good luck in the replacement of the modules. I hope it works as well as it did for me.

You mentioned earlier if there was an "aftermarket" option for these modules. I did extensive searching for this unicorn also and came up with nothing. Further thought on the matter lead me to feel that the money for the modules, even as expensive as they are, is cheap insurance for the overall safety of the operation of the plane. When all was said and done, I still feel it was money well spent.

I would ask you to consider looking back at post #12, telling why, when I did the conversion, I went to the latest model module, the 6x6. The newer module is more readily available and far less expensive.

[Dusty]

I agree that changing modules is cheap insurance,they are cheap compared to a damaged aircraft or a helicopter recovery,everything has a finite life,my modules are 20+years and 1200hours old,these things get a bad rap but have done ok!
I wonder if the rumer mill has confused the "unicorn"replacement modules with one of the aftermarket ignition systems available that have a similar function?

[Paul Z]

I have a set of 6X6 used modules for sale. I replaced them after my recent fiasco with Kickback eating my spray clutch. It turned out I had a Carburator problem on the pilot sided. I had both Carbs rebuilt & replace the Sprag clutch. When I pulled the engine I opted to go to the Soft Start Modules even though they were functioning properly, because I did not want to go through the pain of replacing the Sprag clutch again. If you are interested I would willing to sell them to you at a very reasonable price.

[WWhunter]

Paul,
If he doesn't want them, I may be interested.
Keith