Rotax ignition question

by Mike Blackburn in General Tech Discussion 6 years ago

Dumb question, but does anyone have any resources which explain the difference between conventional (Magneto) ignition, and the ignition systems found in the 9-series Rotax engines? What is the difference between Lanes On the 912/915 and the ‘magnetos’ on the 914?

Really struggling to figure out and the 914 manual is very brief on the topic of ignition (1 half page...)

Thanks

Re: Rotax ignition question

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 8k

A conventional Magneto is a stand-alone device that connects to the engine similar to a Distributor.
The engine connection is strictly mechanical.
The Magneto contains all the magnets, ignition generator coils, Points, and Spark Coils.

The Rotax 912/914 conventional ignition has the Ignition generator coils and trigger coils (Solid State Points) within the Engine Alternator housing. The Electronic Ignition Circuits and the Spark Coils are Separate assemblies mounted on the exterior of the engine.
This system is essentially Stand Alone as it will continue to provide the spark to the engine even if the battery and generator have failed.
It is a magneto system in principal.

The 912is/915 fuel-injected engines have dual computer assemblies (Lanes) that control the operation of the fuel injectors and Spark Coils.
This is a power-dependent system that requires the battery and/or generators for power.
These engines are equipped with two independent Power Generators along with the two independent Lane computers.
Along with the normal dual spark plugs in each cylinder, there are also dual fuel injectors,
One plug and one injector on each Lane.
In the rare event that both generators fail, the engine will only operate for as long as the battery holds out.
Usually for about 30 minutes.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

Thank you said by: Mike Blackburn, RotaxOwner Admin

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Re: Rotax ignition question

by Mike Blackburn » 6 years ago

Mike Blackburn

5 20 23

Thanks Bill. That helps.

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Re: Rotax ignition question

by Al C » 6 years ago

Al C

63 138 106

Hi Bill...

you wrote, in part.....

"....A conventional Magneto is a stand-alone device that connects to the engine similar to a Distributor.
The engine connection is strictly mechanical.
The Magneto contains all the magnets, ignition generator coils, Points, and Spark Coils...."

A possible minor quibble with your otherwise enlightening explanations:

I'm pretty sure engines that feed power to th plugs via a mechanical magneto don't have points anywhere in the system. Simpler that that.The timing of the pulse is supplied by the time when the magnet spins by its generation point.

https://science.howstuffworks.com/question375.htm

Al

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Re: Rotax ignition question

by Bill Hertzel » 6 years ago

Bill Hertzel

13 1.95k 8k

Hi, Al,

Read closely in the paragraph to the Right of the picture showing "The Two Magnets" where they talk about the "Switch in the electronic control unit " Opening. That is the Points. It might be a mechanical switch or an electronic equivalent, but they all perform the function of good old fashion Points.

Contrary to what might be commonly assumed, The moving Magnets build up a current in the coil and then the Points STOP the current, causing the field to rapidly collapse causing the spark. The Spark happens when the Point OPEN.

Bill Hertzel
Rotax 912is
North Ridgeville, OH, USA
Clicking the "Thank You" is Always Appreciated by Everyone.

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