Airfilter Maintenance by Gordon

Another speil by the legendary Gordon:


I probably wouldn't do all this if I had only one or two
foam air filters, but I have a total of 14!... four for the
KTM, three for the XR400R, and one each for the push mower, riding mower, leaf mulcher, leaf blower, hedge trimmer, weed eater, and chain saw. I keep the spare clean filters in plastic bags, and when I change one, I just stuff the dirty one into the plastic bag I took the clean one from. When all four KTM filters, or all three Honda filters are dirty, I gather up ALL of the dirty filters, and stuff them down into my cleaning bucket for about an hour.

Cleaning Bucket: I bought a 5-gallon paint bucket with a sealable lid from a hardware store, in which I put four gallons of kerosene. The bucket needn't be very wide, but it needs to have a sealable lid, and it needs to be at least 10" deep (14" is even better). By keeping the bucket sealed when not in use, the evaporation factor is practically nil. By using a deep bucket containing several gallons of kerosene, the dirt from the filters settles to the bottom of the bucket, leaving the cleaner kerosene on top. I have no idea how long
this bucket of kerosense will ultimately last, but it should last for several years, at least. It is, after all, primarily just to dissolve the old air filter oil, and to wash away some of the dirt, which settles to the bottom of the bucket.

After the dirty filters soak in kerosene for about an hour to dissolve the oil, I squeeze and reimmerse each one several times to flush out the old oil and most of the dirt. Then I let the filters sit outside for about an hour to allow some of the remaining kerosene to evaporate. It is not necessary that they dry completely.

Then I pour 1/4 cup of dishwashing detergent, 1/4 cup of clothes washing detergent, and one cup of gasoline into a regular bucket, and then fill to about 2/3 or 3/4 with warm water, mixing the ingredients well.

Warning: This concoction forms a very strong grease and oil solvent, so it also tends to dissolve the natural oils in your skin. Don't be surprised if it irritates your hands. I usually don a pair of rubber gloves at this point.

The dirty filters are stuffed down into this bucket and left to soak for 10-15 minutes, after which they are squeezed and reimmersed as many times as needed to clean them thoroughly. Once they're all cleaned this way, I rinse them thoroughly several times in clean water, and then hang them up outside to air dry. Sometimes I hang them in front of my garage fan.

Air Fllter Oil Bucket: I bought a tall, sealable, six-quart
plastic kitchen container, into which I poured three quarts of Bel-Ray air filter oil. This stuff is blue, and very, very thick and sticky! It's so thick and sticky, it reminds me of the STP oil treatment I used to add to my old cars! It's so thick, in fact, that I also added about a pint of gasoline to it, just to thin the oil a little!

Once the filters are completely dry from their water rinse, I totally immerse each filter in the air filter oil (still
using the ruber gloves, here), squeezing the filter several times to make sure it is totally saturated. Then I remove the filter and squeeze (but do not wring) out as much oil as I can, letting the excess drip back into the oil container. Then the filter is again set outside for an hour or two to allow the gasoline thinner to evaporate. The clean and freshly oiled filters are then either put back on their respective engine, or placed into a clean plastic bag until needed. The rubber gloves are then rinsed off in the soap/gas/water bucket, and saved for the future use.

This sounds rather time consuming and tedious, but most of the time involves drying time, during which I do other bike related chores. Aside from the drying time, it really takes little time at all, since I keep the sealed buckets on hand and ready to use all the time.

It works for me, and I've found it much easier and quicker to do a lot of filters at once, than it is to do just one filter at a time as needed. This job is too messy to do very often!

I know some guys use 50 wt. motor oil as air filter oil, and I agree that it works fine if you clean and re-oil the filter after every ride. But most of the regular motor oil will drain down and out of the air filter within a week, leaving the filter with very little oil remaining. I've tried it, and I don't like the way the filter looks and feels after a few days. And I certainly don't think air filters need cleaning after every ride.

After trailing behind others on a very dusty ride, of course they do, but not every ride is in dusty air.

I also like to brush on a thin layer of general purpose grease everywhere inside my airbox, before and after the air filter, right up to the carburetor. I like to think that any dirt that gets trapped in the grease, is dirt that my filter and engine never have to deal with.