Abstract: A combination carburetor backing plate and crankcase breather for a motorcycle engine having at least a pair of cylinders, a cylinder head mounted on each cylinder, and a valve for connecting each cylinder head to the crankcase for venting the same through an exit port in the cylinder head. The combination includes a plate having a first side adapted for mounting to a carburetor and to the cylinder heads, and an opposite, second side adapted for mounting an air cleaner. The plate has a centrally disposed first aperture that coaxially aligns with the carburetor throat, and second and third apertures that align with the exit ports on the cylinder heads. Hollow bolts are provided for insertion through the second and third apertures for threaded attachment to the exit ports, whereby the second and third apertures communicate with the exit ports.