Rotax 80hp, ignition problems

[Wheels]

Jorge,
I watched the video and have seen that in my engine. I fixed it by replacing the 1. worn carburetor sockets (rubber part at the flange)
2. adding the rotax recommended tension spring from Carb to manifold. (the engine in the video is missing the spring. It dampens movement)
3 repaired the cracked engine mount.

your mount may have a crack you haven't found or I suspect your prop is out of track or if ground adjustable, has a blade out of angle with the rest.

when you changed engines, did you keep the same prop, prop flange, gearbox etc?

[jrevens]

That's what I was thinking, Wheels - everything you said. If it's doing like the engine in the video, the carbs are jumping all over the place... no way a carburetor can work properly like that. I also believe that I'd check the propeller balance again, preferably dynamically.

[Wheels]

don't forget that the image you are seeing in the video is a product of a video shutter speed that exaggerates the movement. Still, it highlights the excessive movement of the carbs. I could send you the one I took of my own engine but they look identical.
Watch AVwebs video tachometer film. its a trick I learned from Brian and Carol Carpenter but its spot on. It illustrates the shutter speed deformation of imagery from a rapid oscillation or a propeller movement.
Jay

[JorgeEC-YUQ]

Thanks for your inputs.

The carburetors sockets are new, the spring is there and meets the 40 mm length as per manual. I inspected the engine mount again for cracks today and couldn't find anything obvious ... I am planning to use this special coloured spray which penetrantes in the cracks (don't know the technical name)...

What should be the torque in the attachemnt bolts of the engine mount to the frame?

Jorge