Place filter in a suitable vessel. Mix cleaner with water. Depending on the degree of contamination, the dosage must be between 1:5 and 1:10 (1 part cleaner to 5 to 10 parts water). Plunge the filter entirely into the cleaning solution and allow to work for 5-10 minutes. Then carefully knead the filter in the solution until it is completely clean both inside and outside. Do not under any circumstances wring the filter out, as this could cause damage. Then rinse the filter out under fresh water until the cleaner has been flushed out completely. If any stubborn contamination remains, repeat the process if necessary. Allow the filter to dry in the ambient air before installation. Then treat with LIQUI MOLY MotorbikeAir Filter Oil (item no. 20308).