Is Emma park still open or Motorcycles. If so, where do I get some info on hours and such?

Yes. The park is still open to motorcycles.

Actually, as I understand it, the park is for motorcycles,
and open to mountain bikes.

In case you've never been there before you should know
that the trails are generally rocky and technical - see the
other threads on this forum for more info.

The park curfew is 10PM to 7AM according to the signs at the
entrance. The phone number displayed for more information
is (512) 346-1831 - Austin Parks and Recreation.