I see you got many replies, none of which address your question.

I don't think there is a FAR that prohibits training in an
experimental, but your operating limitations more than likely will,
with possible exceptions. Many of the FARs explicitly state that they
don't apply to experimentals (Part 43, for example), but the FAA adds a
few rules back in that it considers important by stuffing them into
your operating limitations that come with your airwrthiness
certificate. For example, the OLs for my RV-6 state that it cannot be
used for commercial purposes, including flight training. It can be
used, however, for my personal training, and in fact it was used for me
to earn my tailwheel endorsement. I can't turn around and use it to
train another student, though. Nor can I use it to tow a banner. It's
hard to guess how they're going to view a Hummelbird compared to
something like an RV-9A.

This will more than likely ultimately come down to a "negotiation" with
the FAA inspector that signs off on your airworthiness certificate.

Caveat: I'm not a lawyer (which I'm sure will be well proven in the
ensuing and inevitable flames), and I could be completely full of crap
(which will also be alleged). I can only tell you what's in my OLs
because I've read them. I don't know what your experience will be.
Best bet would be to contact the airworthiness inspector at your
regional FSDO - he's the guy you'll be working with.

Chris Wells wrote:
I'm building a Hummelbird, and I was hoping to use it towards my private
pilot's license, but I've heard that I can't use an experimental for
flight training. I looked through my FARAIM '97 and I can't find
anything to verify that. Has anything changed regarding this since
then? Can someone point me to the relevant regulations?


--
Chris Wells