914 Bigger RPM Drop and Running Rough on Right Mag

I'll add that it's the coldest it's been run since last year.  It's been running just fine (including run-ups) up until today.

HI Craig

We have seen this a lot on certain aircraft/prop load conditions.  Given that the RPM ignition check is at 4000 RPM that is a very lean burn zone,  normally just a transition area of running.  Simply adjusting the needle clips to one richer will usually solve the issue.  Your correct that the colder weather with the dense air is the problem, it is just a bit too lean for those conditions.  If you fly a lot in colder weather leave it a bit rich in the mid-range  In summer you can go back to the normal settings.

Cheers