Greasing the lip of your air filter. Is it REALLY necessary?

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Guys,

This has had me questioning the logic for years.....

Ok, we all know that everyone, and I mean everyone, says that you MUST grease the lip of your air filter, or use one of those sealing gadjets to ensure that no dust leaks around past the sealing edge of your filter.

It's been accepted practice for at least the 37 years I've had dirt bikes, I know that much.

For the record, yes I DO grease the lip of my filters.

And yes, of course it's piece of mind .... etc. etc. (Not interested in that.)

But stop and actually think about it for a second......

Here you have a foam filter, completely soaked in special air filter oil, with say for arguments sake, air pockets within that foam that are say 1.0mm in diameter.

You squash all those 1.0mm, oil soaked holes down to 0.0mm (ie no voids at all) under the plastic air filter cage when it's tightened down in place properly.

How the hell is dust going to get past a void that simply isn't there? There is nowhere for the dust to go.

While ever the cage remains in place and is squashing that filter down, it forms a perfect seal against dust.

I'm going to put it out there that the need to grease the lip of your filter is possibly an old wives tale that is no longer necessary.

Ok, I have my fire-proof jacket on now ...... shoot !

Greg :bonk:

Ive always wondered the same, but because I oil my entire filter. Meaning I oil the lip, so is it really necessary to add grease over the oil? or should the oil be enough? I always ensure the filter sealed good, I run my finger all the way around pushing the filter against the cage to make sure its not kinked/twisted. It doesnt really matter I still do it. I buy the no toil 3 pack so its not like I have to spend extra money on the grease. It sure would cut down on maintenance on the airbox! :bonk:

The sealing lip is the part of the filter most likely to let dirt in. You're prolly safe without greasing it, if you are well oiled, and properly fitted. I have noticed after really dusty days, when ya pull the filter, it's remarkable how far the dust penetrated at the seal. I grease mine for that safety element.

good point Greg, probably not needed but id rather take 2 mins longer each time then pay for a dusted motor..

NEVER seen it as an issue - the ring on the filter cage makes a positive seal with the Airbox, you just have to tighten it properly - too loose and yes - dust can get in, too tight, and you can damage the lip. just nice and snug and you will never have a problem.

I believe that the grease "designed" for the lip is just another product invented as a pure cash grab through putting a little fear into you.

They make grease specifically for air filter seals? I'll be darned, new one for me.:bonk:

I always used wheel bearing grease, and also wondered about the nesessity of using any at all. Sure is a mess but I'll probably keep using it. Anything to boost the piece of mind factor when several miles back out in the woods.:bonk:

I have a friend who raced mx on thick sandy tracks for more than 10 years and NEVER used grease.He also had good reliability with no breakdowns. I on the other hand put the grease on (as others) for safety sake. I think if the filter is well oiled AND in place you will be fine. The flange parts foam is in any case wider than the air filter foam(so good seal). BUT, if the bike is alittle older and things are not lining up so great anymore, or you cant get your fingers in there to check the seal then grease WILL maybe save the day!!:bonk:

It really depends on how the air cage fits to the airbox. On some bikes the cage simply doesn't fit tight enough to the airbox to prevent dirt from passing through. When possible I modify the filter cage on all of my personal bikes so that it clamps the filter tight against the airbox. I never grease the lip and have never had any issues of dirt passing.

I used to grease the lip then I got tired of cleaning the old grease/grit off. I just spray some oil around the lip and let 'er rip.

No grease for me.

But not all air filters are the same. My buddy's banshee filters just slide into place and I think the seat pushes down on them. Not a great seal, so I'd grease it if it were mine. But he's a quad rider, so he doesn't service the air filter until it starts to run poorly. Every 400 hundred or so hours when changing the tranny oil.

I have always greased mine, for piece of mind. But also, where the filter sits on the boot, this is the weakest are. The filter bolt is in the center of the filter pulling it tight. The force of the bolt being screwed into the boot is displaced throughout the weak ass plastic filter cage. So I grease mine to make sure there is a solid seal and hopefully reducing dust/sand from scaring the vitals.

MAX!!!

I have had several makes and years of dirtbikes, and I have never used grease.

I have never seen any dirt get through. Nothing in the air boot, nothing anywhere nohow however I look has anything anytime ever made it past the filter.

I feel sorry for you guys who have to clean up that greasy mess, but if you sleep easier at night, it´s your choice:thumbsup:

The problem with that "perfect" seal is that the filter cages are often made from flemsy material that is subject to warping. If you have a aluminum cage, my vote is no it's not necessary. If not, it's "probably" still not but why chance it?

I've heard the arguement often that the grease is just too messy but, IMO, that's not true. I apply it directly to the airbox base with an acid brush and it cleans up easily with a small brush and WD-40. Not a big deal.

I have had several makes and years of dirtbikes, and I have never used grease.

I have never seen any dirt get through. Nothing in the air boot, nothing anywhere nohow however I look has anything anytime ever made it past the filter.

I feel sorry for you guys who have to clean up that greasy mess, but if you sleep easier at night, it´s your choice:thumbsup:

I would like to invite you to the next Desert 100 harescrambles next April, here in WA state. We'll have a vid cam ready to check that airbox when it's over :bonk:

http://stumpjumpers.org/2009/09/28/2010-desert-100-date-set/

All that Mt St Helens ash, and talcum silt gets everywhere. I don't think Sweden has dirt small enough to go through an oiled sweat sock :bonk:

The problem with that "perfect" seal is that the filter cages are often made from flemsy material that is subject to warping. If you have a aluminum cage, my vote is no it's not necessary. If not, it's "probably" still not but why chance it?

I've heard the arguement often that the grease is just too messy but, IMO, that's not true. I apply it directly to the airbox base with an acid brush and it cleans up easily with a small brush and WD-40. Not a big deal.

It's even easier than that. I use no toil in the tube, it is water soluble. I just squeeze it on the filter rim and install it. When I remove the filter for cleaning, the grease cleans off w/ the filter cleaner. If there is grease left on the boot, I just wipe it off w/ a rag.

http://www.slyfoxmx.com/pd_notoil.cfm

MAX!!!

Thanks for the invite, but I only ride MX.

We have some pretty silty sand tracks here in Sweden, you are welcome to try them out, grease or no grease:thumbsup:

I never grease the rim of the filter and have never had dirt get past. Granted Yamaha has one of the easiest access air filter boxes around too. I dont know how you guys on the Honda's Kawi's and Suzuki's change air filters at the track without cleaning out the entire air box before removing the old air filter. Theres just not room to manuver on those bikes. That being said my son is switching to Suzuki this year. Any Suzuki owners have any tips?

its just a peace of mind to know dirt cant get through there..

I never grease the rim of the filter and have never had dirt get past. Granted Yamaha has one of the easiest access air filter boxes around too. I dont know how you guys on the Honda's Kawi's and Suzuki's change air filters at the track without cleaning out the entire air box before removing the old air filter. Theres just not room to manuver on those bikes. That being said my son is switching to Suzuki this year. Any Suzuki owners have any tips?

hondas arent that bad, the yam. has a very open box but with the hondas you just rotate the filter and it comes out easily.. only problem with the hondas is the airbox seal

hondas arent that bad, the yam. has a very open box but with the hondas you just rotate the filter and it comes out easily.. only problem with the hondas is the airbox seal

Yeah. I wondered if it was just having the right technic on the Honda's. I think Honda fixed the air box seal issue though didnt they?

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