Gene Underland wrote:

"The IA he is working with recomends he take the choke out of the
cylinders."

Your friend best get a new wrench (IA). Sounds like this IA is setting him
up for needing his cylinders topped in a fairly short time - probably at the
next annual when he's informed that the compression(s) are too low.

The choke is in there so that, at operating CHT's, when the upper portion of
the cylinder expands slightly, the walls are parallel. Take out the choke
and the upper part of the cylinder will be larger than the rest of the bore
when hot. Not a good thing.

If choke was unnecessary, the manufacturers wouldn't bother - it would
certainly be easier to machine the jugs without it.

Dan Schaefer