chuck wrote:
I know that just about everybody has bad-mouthed the 2si, but what are your
opinions of the Hirth series?

I do not know about all of them but I have had great experience with
a 3203 (fan cooled). The basic concept of nikocil/aluminum jugs is very
sound for air cooled engines. It is how Porsche 911s were made back
when they were aircooled.
As for the 2si, I would take another look at the new ones with the
larger flywheel - ignition trigger spacing. That should have cured
their ignition issues.