Home-made Airfilters

Cman250

Dude Guy Bub
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#1
Well a buddy of mine dirt bike's had an old air filter that had "bit the dust"<---no pun intended. So we had to order a new one and instead of waiting for it to ship we built one. Using layers of paper towels and a rubber band, put holes in the layer (about 4-5 pen size openings) then on the second layer no holes but it has to be dampened with a very light oil to help capture all the little dust particles. Then wrap the rubber band over both layers and onto the hose that connects your air filter to the carb. It is like an engine condom so to speak, and from what I can tell an easy alternative to replace you broken air filter if your stuck out in the woods with just a rubber band and paper towels. It seems to filter well, but I would like a second opinion: Am I hurting the engine by doing this?
 

XRpredator

AssClown SuperPowers
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#3
I've peeled the skin from the fruit of the Yambi tree for one layer, and then stripped bark from giant ferns for the more porous outer layer. Worked like a charm.
 

RM_guy

Moderator /
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#4
What you did is technically OK but personally I wouldn't use it. Oiled paper filters have been around for a long time but the paper is not a paper towel and it is protected from damage. Also, great lengths are used to increase the surface area of a paper filter by adding a lot of folds into it. Since what you did is a lot more restrictive you will be choking the motor and it will run rich. You run the risk of the paper towel tearing as air is being sucked through it, or from at stick, rock, etc.

My advice is not to use it.
 

Cman250

Dude Guy Bub
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#5
Ok thanks for the advice. The filter itself was incased in a large protective box that made it near impossible for any large objects to enter it in the first place, and I did a suction test to make sure that the force at max rpm could not break the filter. Compared to the old filter this one is like a K&N, i don't notice it choking much but the only reason it was built, was to entertain and keep the bike running while I waited for the real filter to be shipped so I took my chances. I could probably build a better one , all i would need is some wire mesh.
 
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#6
If you have an air filter disabling emergency in the middle of nowhere (does that really happen?) you'd be better off running no filter at all than a filter made of paper towel. I'm really supprised it didn't get sucked into the engine as soon as your buddy revved it.

If you're trying to keep the bike running until you get the real filter, this is not the way to do it.
 
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#7
i guess its a good idea but if i was stuck in the woods with no filter id probably just run with now filter like 76MGC1500 said and anyways who goes trail riding with paper towels (maybe some people if its muddy) and a rubberband?
 
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#10
I stopped using a real filter a long time ago. I found that "DEPENDS" adult diapers work much better and I can get them for free from my grandfather once he is done with it. ;)
 

Green Horn

aka Chip Carbone
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#11
No matter what shape the old one was in, I am pretty sure it's better than some Bounty and a friggin' rubberband. You would have been better off to just wait till the new one got in.
 

Cman250

Dude Guy Bub
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#12
Green Horn said:
No matter what shape the old one was in, I am pretty sure it's better than some Bounty and a friggin' rubberband. You would have been better off to just wait till the new one got in.
Well lets just say the old filter had not been changed since umm...well it was the original after 4 years of hard abuse. In fact i tried to clean it but the filter riped and there were several holes in the filter that could have let in large objects. We probably should have just not used the bike at all and waited till the filter arrived. But driving is my fix and if I go without it for a while, worse things would have gotten broken than have now....atleast yet.
 
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#13
I had the air filter assembly snap off my Triumph (spitfire, not a bike) at work one day. I made a filter from tinfoil and coffee filters to get home with. There was a lot of road construction on my way home, and I figured it would keep the dirt out. :)