DIY Foam Air Filter

[RedRocket]

As I've been going through bikes recently the prospect of spending $ 40 + dollars for a new air filter makes me squirm. Now I'm not the first person to do this, and a friend of mine did a little show and tell himself a few years back. While I was work one day I was inter-noodling and found that UNI-Filter ( makers of foam filters ) was only about 10 miles away from me.

With a bit of snooping I found that UNI Filter sells a replacement filter for my bike for about $ 32. Being the KLR-like rider that I am I could buy a 12 x 16 inch sheet of UNI Filter foam for only $ 14.99 so that's what I did. I zipped out at lunch, and picked up some filter element

The camera was handy so I figured I'd expend a little effort, and share my actions with you all.

 

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Here's the filter element along with some required tools.

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Here's the dirty starting point. This is the air filter from my 88 Venture Royale. I only added the Royale in there because I like saying "Royale". It's about $ 45 to replace at the local Yamaha store.

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I started hacking out the paper filter element with a pair of scissors, and box cutter.

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I was being careful not to jack up the wire backing.

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That's a long hunk'o'paper.

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I then used needle nose pliers to pull out the sticky bits. Notice that foam sealing ring is also rotten. I'll pull that off, and replace it too.

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Here's the filter cage cleaned up and ready to start construction.

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I cut the filter element to fit. Make it a little thicker than needed so it'll bond better. No matter which way I cut it, it required two sections.

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Before the next step where I was going to handle smelly, sticky stuff I had to start dinner.

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While I was at UniFilter I asked the guy who was helping me what I should use to glue down the foam he recommended some brand of industrial glue, which I didn't have. He also mentioned that I could use silicone gasket sealer, and I had that so I was off to the races, and started laying a bead.

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Here it is stuck in place. I used a strip of packing tape over the joint and let it sit for the night.

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After drying up for 24 hours I went back at it with the silicone to make doubly sure it's well mounted, because remember that in the future you'll be squeezing, and squishing this when you clean it.

I stopped at LOWE's on the way home, and picked up some foam tape for $ 2.43.

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It's ready to use, and I still have over half of the filter foam left to use on another bike or two. :thumb

[RedRocket]

Epilogue; instead of paying $ 15.00 for Uni foam, a craft, or material store sells the same stuff for less.

[Condor]

Hey Rick, Thanks for posting the DIY info... Looking over the online catalog for Unifilter I ran across these which would probably just fit over the crank vent when getting rid of the vent hose. 3/4"x2"Dx4"H, and at $7.95 they ain't gonna break the bank. I think I might try one of their replacement filters instead of building one. Not that you didn't do a great job, but for the $15 buck savings I'll go the easy route. BTW in the FAQ section they suggest rejetting??

 

http://www.unifilter.com/online%20catalog/universal%20filters/socks_lg.jpg

[RedRocket]

I didn't notice any change in running, or fuel economy.

[GaryZ]

Excellent write-up . . . Thanks!

[Ivan]

Now I am really wishing I hadn't thrown out my old airfilter.

[Big69]

Great write-up one question about the glue or gasket goo could the filter be tapped with long bolts to hold the foam so the next change is faster ?

[eazyduzzit]

So you're the one who eats coucous! I was wondering who eats that stuff...

[RedRocket]

Great write-up one question about the glue or gasket goo could the filter be tapped with long bolts to hold the foam so the next change is faster ?

 

 

I'm hoping the filter material will be staying right where it is. The idea is that you use air filter cleaning solution like you do on a K&N filter, and you won't have to replace anything next time, except clean, and re-oil it.

[RedRocket]

So you're the one who eats coucous! I was wondering who eats that stuff...

 

 

You should try it. Plain, or Parmesean are my favorites. It takes 1/3 the time to cook compared to rice. It's just wheat anyways, nothing too exotic.

[lvsloan1]

If I go to a craft store what's the foam called that I need if it's not Uni-foam brand?

[Flyinfool]

Whatever you buy at the craft6 store, do some testing. I'll bet the stuff made to be an air filter is also chemical resistant, at least to gas and oil and methanol. The stuff from the craft stare is made for pillows, it does not need to be chemical resistant. you must also be sure that the stuff from the craft store is an "open cell foam", most cushions are a "closed cell foam", better cushioning and will not absorb spilled liquids.

[gggGary]

Just did this on my RSV when I found mr. mouse had been busy. I use a zip tie to secure the foam and remove it to clean and reoil. The foam is a tight enough fit I'm not worried about air dirt getting around the edges. The paper was separating from the end with the hole so I finished the job and glued the screen to the cap with flexible bumper epoxy (handy stuff) I have been doing similar on my XS650's for years. One sheet cut in half the long way then trimmed down a little more does both filters on the RSV only one seam per filter. Not shown but I bent up some soda can aluminum to keep the seam airtight. I also replaced the mushy foam seal with some black UNI foam. Note Uni sells several different foams from coarse to fine hole size. 42 MPG on the first tank run this way.