Number 4 cylinder running hot!

Hello Roger, thanks for your advice.

The engine was used with 450 hour on it and I recently installed it on a gyro.  The clip position on the needle is the 2nd groove from the bottom.  The main jet that was in it was 155 and all of the new plugs are still white (no glazing or rounding of the electrode) with 8-10 hours on them.  What is the stock size?  I put a temp gun on the same spot of #3 and #4 and #4 was almost 200F hotter.   I ordered some new O-rings for the intake manifold.  The engine is a 2008 ULS so maybe it is leaking there.
What's the best temps for the ULS? 
Thanks!

I see that the carbs have the standard jet which is 155 and the clip is also in the standard position.

I also have another rotax owner post about losing 1000 rpms when performing a "mag" check.  One drops just less than a 100 rpm and the other one has a definite problem.  Tomorrow I will check the gaps between the ignition pickup and the flywheel/stator.  My guess though is that the some of the pickup are probably bad.  The engine runs very strong so I cannot figure that one out yet.

Could the mag check issue be related to a hotter cylinder issue?

Thanks.

This could easily be just a wire or trigger coil gap.I had one like this a few months ago and it was just a wire. Drove two of us crazy. Someone has swapped two wires.

Good morning Roger.
What wires were swapped and what did that do?  I will check that today.  I did swap the two red stator supply wires that go to the two igniter boxes.  I did that to see if the stator was the issue, but the problem stayed on the same switch.  I had also swapped the igniter boxes 6-pin plugs to see if the problem was caused by some between the plug and the sparkplugs.  Again, the problem stayed with the same mag switch. One thing that strikes me as odd is how well the engine runs and yet it does so poorly on a mag check.  The plugs all look pretty much the same.

And you think that the trigger coil set could possibly raise the EGTs on one cylinder? That would be neat if the hot cylinder's EGT problem was related to the trigger coil set.

Thanks!

Just checked the coil pickups.  One was at .010".  Adjusted it and tested the ignition out again.  The kill switch issue did not change.

Roger, any chance that you could look at my other issue please?
https://www.rotax-owner.com/en/912-914-technical-questions/9368-912-uls-with-460-hours-built-in-2008-1000-rpm-drop-during-mag-test

As far as this hot #4 goes, I'm waiting on some new intake o-rings to come in.  Maybe an intake leak as you said earlier.  This is after all a 2008 engine. 

If not, I guess that it would have to be a ducting issue.  I made a carbon duct that hopefully will draw a vacuum from the prop.  It probably won't work, but I wanted to try it before creating some deflector plate for #4 that just catches passing air.