Abstract: An improved centrifugal air cleaning system including a fan, a fan volute defined, in part, by a curved outer wall and a base wall, and a deflector wall projecting from the base wall intermediate the fan and the outer wall. An air inlet port is formed in the base wall and is located between the deflector wall and the outer wall. The deflector wall includes a first wall portion and a second wall portion. The first wall portion has a curvature generally matching a curvature of the fan while the second wall portion diverges from the fan toward the outer wall. The first wall portion prevents radially projected particles from reaching the air inlet port while the second wall portion cooperates with the outer wall to define a restricted flow path downstream of the air inlet port that creates a relatively high pressure condition at the inlet port and injects substantially particle-free air into the carburetor.