Two Carbs instead of one

Thanks for your reply.   The carb bodies are the same physical size just different larger jets in the Jabaru 125HP we can rule out size being the factor in placing them where they are behind the engine instead of below as in the Jabaru.  Having redundancy is also out of the question as unless the two carbs have a crossover between them.  they can only feed one side as designed.  Yes the Jabaru does not have a gearbox on top of the centerline of the engine but reducing the visibility in order to put the one carb under the engine like Jabaru could be the difference between falling out of the sky trying to run on half of and engine and reduced visibility.  Given the option I would think lower visibility would be preferred at least by me.    I look at the Rotax and do not see why a manifold with one carb feeding both cylinders at the same basic location and elevation cannot be fabricated where the two carbs are now,  this would not reduce visibility and eliminate the need to have two carbs synchronized and continuously running. I see the redundancy of having two carbs but only if they are able to feed the whole engine at reduced power or whatever it takes to land.  Many motorcycles have this arrangement having multiple carbs feeding several cylinders but they can pull over to the side of the road when one carb fails. 

 Synchronizing and having two separate throttle cables two choke (starting carb) cables and all that requires just seems unnecessary and has more potential to fail.  I'm still looking for justification for the exposure of needing two carbs without a crossover enabling all four cylinders to continue to run on one.  To me it looks like Rotax designed the 912 to power something else that did not require the highest level of reliability needed for an airplane possibly a motorcycle ?   They aren't very worried about carbs now as they have the IS engine ?

... from the OP  :  They aren't very worried about carbs now as they have the IS engine ?

Mebbe ;  Hopefully rotax did better w/ their IS than my 2013 suzuki quad which was designed w/ a 12 V DC battery that receives AC current from the alternator; therefore a sulfating battery results in fuel starvation ... not so good when you're 25 miles in the desert away from your trailer, probably not so good for 1000' above unforgiving terrain either ... 

talk about progress; 30 years ago i was kick starting my desert bikes when troubled w/ dead batteries ... (inserts crying out loud icon here)...

They may have copied BMW motorcycle engines. These engines, which also use dual Bings, were for a long time (before modern technology) known to be the most reliable motorcycle engines, by far. It was not even close. BMW owned the reliability market for a long, long time.

John...FYI..

  The IS engine like all the other Rotax aircraft engines runs fine without a battery....you only need the battery for starting. The ECU is powered by the stator so as long as the engine is turning it will be fine.