Number 4 cylinder running hot!

Air flow can really be very different from what some would expect. I was going to ask what the tubs were for. I don’t think they’re going to work as you hope. Ram air can help things, but usually vacuum induced flow has poor results depending on location. I would back off the header wrap touching the EGT probes. This can and will cause erratic readings. I did a research project on this in 2007 because I had issues from it. Do the EGT temps change if you remove the air filters? Have you balanced the carbs during this issue? You may have a bad EGT probe? Has there been any recent Maint. and your issue started after that. Check the O ring seal on the carb rubber flange. 

Thanks.   I did see that and I cut away from the actual probe.

And you are right about the duct.  at 3000 rpm and misting water at the duct's inlet showed no movement into the tube.  Maybe is will move some air when actually flying, but I now believe that it won't cut the mustard.
I will start work on a wind deflector for the #4 cylinder.  If it works, then I'll do the same for #3.

Thanks man.

I would caution you against implementing more than one "fix" at a time -this will almost certainly lead to confusing results, unnecessary work and expense.

D'oh!

I pulled all the plugs today.  Something I thought that I did earlier, but I must have been mistaken.

All of the lower plugs had a good bit of black on them.  More so than the upper plugs.  Is that normal for dual plugs?
And all of the plugs were much darker than the #4 cylinder which was pretty much all white.   I thought that they were all pretty much the same so I got that wrong.  Sorry about that.
I had just installed a 160 main jet, but after seeing these plugs I put the 155 right back in.  I believe that Roger said the the stock jet should work fine.  #4 is running hot for some other reason.  Maybe the air leak a the number 4 manifold.  Early next week I should have new o-rings.

Thanks.

I have always felt that "dark" plugs, in a Rotax 9, is due to running at less than optimum ignition timing. This occurs during most ground operations when RPM under about 4500 (the experts will know the specific speed).