Hi Jonathan,
The 912 series engines are designed to be fairly tolerant to a wide range
of stoichiometric fuel ratios. I surmise this because of the absence of a
manual mixture control and the fact that the Bing carbs do close to nothing
in terms of altitude adjustment of mixture as I documented here many years
ago. Note that the Rotax advertisements no longer claim to be altitude
compensating. If anything, in my experience and in chatting with Rotax
and Lockwood tech people over the years is that the engine is generally
running rich and it gets worse after takeoff.
The key purpose of the mag check during run-up is to assess the status
of the ignition system to assure that one has two functioning ignitions.
The first thing to consider in the differential diagnosis of a large RPM drop
on one side of the ignition would ignition problems, e.g., bad or dirty
spark plug, bad cable, bad ignition module, etc. Again, my opinion, but
I would suggest that fiddling with the carb needles when your base
airport is near sea level would be low priority and a low yield procedure.
This is not intended as a criticism as you obvious have substantial
experience, I just think that many reader here, especially the growing
numbers of second or even third generation owners are still just
beginning their Rotax education.
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=448309#448309
|