Air filter maintenance

(By Andy Hanmer)

One of the kindest things you can do for your dirt bike is to be absolutely meticulous about maintaining your air filter after every ride. The reasons are not rocket science: The longer you leave your air cleaner, the more dirt the motor will ingest. The more dust your motor swallows, the faster it will wear out. Valves, pistons and bearings all suffer when the air cleaner is neglected. Here are five steps to air cleaner happiness.

Step one: Washing the foam in solvent

Use petrol, paraffin or one of the proprietary solvents. I use a mixture of diesel and petrol which I buy cheaply from my local garage. They drain it from customers cars after the attendant has put the wrong fuel into the tank. Stuff to remember: Always use gloves when you are handling petrol. Gloves are cheap enough from Dischem, cancer is worrying and expensive. Also, when you need to dispose of the used solvents, phone The Rose Foundation or a similar organization and let them take it away. Please don’t pour it down the drain.


Step two: Washing the foam in hot soapy water

I use ordinary dishwashing liquid, and I do it twice before rinsing the foam thoroughly, and putting it out in the sun to dry. This is a good moment to mention that you can save time by buying several spare air cleaners. Use them one by one then wash them all at the same time. You can keep the clean ones in zip-lock bags until they are needed.


Step three: Soaking the foam in filter oil

A messy task. I make it less messy by keeping my foam filter oil in an air-tight, air-cleaner sized Tupperware. Dip the filter into the sticky muck, then squeeze the excess out. The air cleaner should be a uniform colour when you are finished.


Step four: Grease the flange

Fit the filter onto its cage, then smear a line of grease onto the flange where the air-cleaner meets the air-box. This will prevent dust-laden air from leaking past the filter. An essential step. Use cheap grease for this. No point in using up your expensive waterproof grease when wheel-bearing grease will work just as well.


Step five: Clean the airbox

You do this mainly to stop dirt falling into the intake boot when you are fitting a clean air cleaner. Some people like to fit an air-box cover over the intake boot, then jet-wash the inside of the air-box. I prefer not to, for two reasons. A lot of air-boxes these days contain the battery and the starter solenoid, and I don’t like mixing water and electrical components. Secondly, from time to time water leaks past the air-box cover and into the carb, so then the carb has to be cleaned out. I wipe the inside of the air-box with a cloth dipped in thinners. I also check carefully that there is no grit inside the boot, and up against the back of the carb.



After you have installed the fresh air cleaner, run your finger around the edge, to ensure that the cage is not sitting cockeyed and leaving a gap for dust to flow through. You’re done. Polish your halo and get into the bush.

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