A primary housing for a motorcycle engine includes an inner housing that
defines internal coupling apertures, transmission coupling apertures, and
external coupling apertures. Internal fasteners extend through the
internal coupling apertures and the transmission coupling apertures to
couple the inner housing to the crankcase and the transmission. An outer
housing defines coupling apertures that align with the external coupling
apertures and fasteners extend through the coupling apertures, through
the external coupling apertures, and into the engine crankcase to couple
the inner and outer housings to the crankcase. A resonant damping device
is rigidly or moveably coupled to an anti-node region of the outer
housing to reduce noise emissions from the outer housing during engine
operation.