Your filter can lose its shape if dropped or handled without care. Lightly blow compressed air (50 Psi max.) from the inside out to loosen particles. Use a garden hose with spray nozzle (low pressure) and rinse from the inside out. Use either dishwashing soap, Castrol Super Clean, or Simple Green with water if heavily soiled and air dry.
Oiling (aerosol spray recommended):
Oiling is required for dirt track use. First time oiling requires air filter oil (Amzoil, K & N, Klotz, Spectro)