Hi Paul-

Apparently a rotary in full song is not very subtle.   (snip)

One strange behavior -- when we shut down, we seem to always have a
single 'backfire' around 1 second after everything stops moving.  I'm
guessing we're super rich at the bottom end or something.

Mark (Rocky Mtn High)

My 12a was named "The Screaming Banshee"... for a reason!!   It was hard to
stay in the same county (much less 3' in front of her!) when she was singing
at 6000 - 7500 rpm!!!   Even the Active noise attenuation headsets weren't
enough to keep the ringing ears protected!!  The Banshee had 2 mufflers!  I
even labelled the throttle with a "Volume" sticker!

I noted on the engines with carbon build up on the face(s), that the
backfire would occur on shutdown... our fix was to squirt each troch face
with 2 stroke oil in the spark hole, let it sit overnight, then fire it up
the next day or so, run it hard for an hour or so (and smoke the countryside
for a bit!).   When I shut it down, it didn't backfire any more!  I ran the
low octane stuff with TCW-3 added to the gas... a little over half an ounce
per gallon fuel.

Gary Buster
Tyler, Texas