A breather assembly for a motorcycle engine includes first and second substantially identical rocker supports that are each coupled to a respective cylinder head. Rocker covers are coupled to the rocker supports and cooperate therewith to define respective rocker chambers. Each rocker support defines a first breather passage and a second breather passage. A first breather assembly is coupled to the first breather passage of the first rocker support, and second breather assembly is coupled to the second breather passage of the second rocker support. A gasket member positioned between the rocker supports and the cylinder heads obstructs the unused breather passages of each rocker support. A sealing member is also provided that seals the interface between the rocker support and the rocker cover, and that also seals the interface between the breather assembly and the associated breather passage.