An air directing device for motorcycles with an engine air cleaner bottom housing. An external air plenum forms both an engine-air intake channel and a rearward cylinder cooling channel by coupling (e.g., directly attaching) the external air plenum to an air filter. The external air plenum defining a forward-facing inlet port and an engine-facing outlet port (disposed over a portion of the rearward cylinder) with the two channels in fluid communication with the inlet port.