Air Filter Maintenance

A dirty air filter or air cleaner as some would have it robs your engine of air which we all know is needed for combustion. What are your service intervals? I can’t find anything on foam type filters but K&N recommends 50,000 miles for their cotton filters. For those of us who prefer metric, that equates to 80,500km. K&N also says that their cotton filters last for about 150,000 miles between replacement. You do the math.

Due to my fussy nature I used to clean my filter once every 4 months when I worked in the oil and gas industry, clocking average mileage of 6,000 to 7,000km between washes. The air around oil and gas processing plants carries a fine dust that settles on surfaces and if you park your car or motorcycle for the entirety of a 12 hour shift like me, you return to find a layer of this fine dust on your machine. It is especially obvious on the chrome. Something you wont see but your filter feels for sure. I procrastinated on my latest cleaning. Its been more than a year since the last one and so I finally decided to pull it out and give it a well deserved wash. I changed jobs a year ago and I’ve clocked about 15,000km since.

Cleaning Products for Air Filter change

So these are what I use for my filter maintenance, K&N filter degreaser, Loctite, some automotive grease, filter oil and some tools for removing the filter housing. This ones fairly easy and took me about 15 minutes to remove.

Air Filter removed on Harley Davidson Dyna FatbobRoland Sands Design Air Cleaner Scrub Bag

I wiped down the surface where the filter sat, removing dirt and grease that could affect the filter seat when fitting it back. That could bypass the filter and let gremlins in, which is of course, a bad thing. I’ve also covered it up after so nothing can find its way down the passage and into the inner workings of the engine where it could wreak havoc.

K&N Cotton Air Filter

This is the inside of my K&N cotton filter. I’ve used a small allen key to gently straighten out the crooked fins. Its a metal mesh over the cotton element but you could still damage the mesh and puncture the element if you are too rough.

K&N Cotton Air Filter in Sink

So this is what a years worth of dirt looks like. I’ve already given the K&N degreaser a good 20 minutes to soak in and do its work. I’ve also used a paper towel to wipe the grease off the rim of the filter and especially from the groove you can see in the first picture.

Washing the K&N Cotton Air Filter

This is what it looks like after washing and gently tapping the filter to remove any particles lodged inside. You’d be surprised what finds it way in. The odd twig or 2, bits of leaves and a little bit of feather I guess must have come from avian roadkill. I’ve rinsed the filter from the inside out, against the direction of airflow during normal use. Don’t use a shower head if your water pressure is too high or a jet either, since that could puncture the element and you’ll end up with a sieve instead of a filter.

Spraying Maxima Air Filter OilLeaving Maxima air filter oil to dry overnight

After airing the filter to dry overnight, I sprayed on a layer of filter oil and left it for a good hour to dry. Filter oil makes the element tacky, like a layer of adhesive that catches dirt, so the filter not only traps dirt but also gets particles to stick. 2 actions in 1! Its also blue, from the Maxima oil. Not the usual K&N red, oops!

Applying grease to the K&N Cotton Air FilterK&N Cotton Air Filter with grease applied

Apply grease to the rim of the element. That will stick the filter to the base of the housing, so nothing can get past on its way to the engine.

Apply Loctite threadlocker to the bolts when installing air filter back on

Loctite those bolts if you want to keep that filter on!

K&N Cotton Air Filter with seam facing downwards

I’ve installed the filter back with the seam at the bottom, you don’t need anyone to see that seam! The seams also got bent while torquing down the bolts, but we can live with that can’t we!

Air filter element cleaned up and reinstalled

And all done! All in, removing, washing that filter and reinstalling it has taken barely 3 hours. Definitely doable over a weekend. In return for my effort, the exhaust note is more defined and crsipy, the characteristic crack of each exhaust stroke is clearer while engine response is sharpened and throttle sensitivity is increased. Time to ride!

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