Ignition

Thanks, Rotax Wizard to confirm my thoughts. I also think so. One question more. In ignition stroke there is only one spark plug ignite in one cylinder, right?. The other one is in stand by mode?

Leo

Nope, a check of the system diagram shows that they fire at the same time.  The flywheel plate has trigger bars that line up both the plugs at the same time.  

Cheers

So 4 plugs fires at the same time. I don’t understand this picture exactly tho

Leo, this is the flywheel and the trigger coils mounted on the housing on the ignition side of the engine.  The flywheel moves counter-clockwise. As the bars move past the triggers they fire the ignition as you can see in the diagram. There are 2 modules and the A module fires both 1 and 2 top plugs and the B module fires the bottom 1 and 2 plugs, all fire the same time.  Given that only one cylinder will be in the compression stroke with fuel on top of the piston the engine will fire that.  The other cylinder has no burnable mixture under compression.  

If you review the description found in the maintenance manual heavy MMH it explains each phase and how the system is redundant.  

Cheers

The magnets on the flywheel are slightly shifted vertically and trigger corresponding pickups in the way that at the same time only 2 cylinders fire all their 4 plugs. At that time, there is a combustible mixture in one of the cylinders, only.

https://www.picclickimg.com/hdcAAOSwrgVdhI3n/80-Hp-Rotax-912-Stator-Magneto-Wheel.webp

The above picture should help.