80ps might be a little optimistic. They can make between 70-75ps though. If you want more than that you need to be looking at Honda RS250's.

A good well sorted motor will make to 68ps. More than that will require quite a bit work as well as a number of parts, eg HRC crank, cases, ignition etc.

65ps is more normal for your average MC21 with normal race modification.
_________________
If I have to take the carbs off once more...