I am considering a project to use a Wankel in a dirt bike engine. I hate
valves.

The engine would be something similar to this one:
http://www.nova-racing.com/nova_gb/index.htm

Do you have insight into this?

One of the things I have been warned about was the angular momentum
these engine create. Norton made race bikes back in the 90s using
Wankels. I have read rumors of this angular momentum as part of the
engines demise. I, however, have not read this by anyone who ever rode
those bikes. Norton went belly up for financial reasons. The actual
riders described the bikes as very lightweight. This is contrary to a
bike with angular momentum forcing the bike straight. They had other
complaints, but not that the bike would not turn.

Thanks for any help.

Regards,

Bill

The Norton engine still lives in UAV's and aircraft.

Check out Rotamax.
http://thekneeslider.com/archives/2006/08/17/small-rotary-engines-for-motorcycles/
http://www.rotabike.com/about-us.html
http://www.rotamax.net/downloads.html

We have not heard from them for a while so let us know how you make out.