It has been many years since working on generators but, if you can't find much on Olympian, contact the engine manufacturer. Typically the engine speed governor comes with the engine.
If the engine is air cooled, check with Briggs, Kohler, Onan, Tecumsah, Wisconsin, Honda, etc.
If it is water cooled, check with Kohler, Onan, Ford, Winco, etc.
Larry
