| Filter Cleaning
K&N, the filter manufacturer, sells both a cleaner and a dirt-retention oil that is available in the UK from Demon Tweeks and others.
Kerosene is commonly substituted as a cleaner/solvent because it's inexpensive and much safer to use than petrol (gas to us Yanks.)
Some filters such as Pipercross have two layers of foam bonded together so harsh solvents like carb cleaner may damage the adhesive or the foam itself. | 
Shazaam!
Threaded Mode