B A R R Y wrote:

Do you taxi full rich?

We used to, which occasionally have us slightly low compression
readings on one or more cylinders in the hangar. The low cylinder
would move, as there was nothing really wrong. G We now lean
aggressively until we get to the runup area, and have never seen the
problem again.

Our home field is 250 MSL.

Can you (or anyone else) explain the mechanism of this? Why a full ruch
taxi would affect compression? I routinely lean the mixture for idle
and taxi because I've learned that at my home airport (KORL) the plugs
can foul between the ram and the run up area. But I don't understand
(and I'd like to be educated) how it affects compression.

John Stevens
PP-ASEL