Foam Air Filter Sucked Down Throttle Body!

[leafman60]

LOL

My BMW G650 single.

I had a high-flow foam filter in the airbox. I had recently cleaned and re-oiled it.  It was 2-3 years old and apparently deteriorated enough to fall apart.   

The throttle began sticking on me and, when I investigated, I found half the filter had broken apart and was long gone! Down the TBody.

The motor runs fine.  I hope it was sucked in and then blown out with the exhaust gases and not melted onto any of the valve faces or piston rings.





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[Idontwantapickle]

Snort!
That really sucks.

[sign216]

I was going to make a joke about a girl I knew who could....

[rodekyll]

I was waiting at the 4-way for the light to change as cruise ship passengers wandered aimlessly through the intersection.  The light changed.  The pedestrians did not.  Rinse and repeat.  After a couple stoplight cycles I saw an opening in the throngs of the walking dead and, whacking the throttle open, sucked my foam air cleaner into one intake, stopping my suddenly rumbling BUBS in mid chorus and the bike in mid-throng.   

It was probably the fastest launch to a dead stop I've ever made without actually hitting a lane divider.  I felt like the cop in that scene from AMERICAN GRAFITTI when they chain his cruiser's axle to the telephone pole.  Guessing immediately what had happened, I limped it around the corner where I unwrapped the foam from the throttle butterfly and went on my way.  I sure showed them! 

[leafman60]

funny

I'm done with foam filters now.

They flow air very well but now I know to inspect and change them often.


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[John A]

I like an engine that will suck the crystal right off your watch!

[Scud]

Thanks for the story. This has motivated me to reinstall the screen on my Husqvarna. The PO had removed the flash-screen between the filter and the intake tubes when he switched to a K&N filter. I went back to foam. I thought the screen was only to prevent possible backflash - but it sure would stop any big chunks of foam filter from getting through.

I once started a 1955 Cadillac with a paper towel left in the intake manifold (from when I had the carb off). It ran a bit rough, but then I just gassed it - and it blew the towel out the tailpipe.

Back to your situation: This might be a good time to run some engine cleaner such as Seafoam.

[steven c]

And oil change !

[Scud]

And oil change !

Excellent point - you can be almost certain that there are some chunks of foam filter in the oil.

[Arizona Wayne]

I've used Uni foam filters for decades and never had something like this happen.  Over many years the foam does harden and disentigrate.  My Unis have wire inside frames so what you explain doesn't happen.   

[rodekyll]

Mine were those blue-ish green foam wads that have a screen.  They were old and freshly oiled.  The mesh deformed into the throttle body (I'd removed the intake snouts) carrying the foam with it.  I was lucky that it hit the back side of the butterfly and jammed the throttle closed instead of opened.   I was able to thump the bike at idle around the corner and out of sight before clearing it out.  I'd switched from K&N to the Uni's because I was told this could happen with K&N's.  I'm back now.

[canuguzzi]

I've used Uni foam filters for decades and never had something like this happen.  Over many years the foam does harden and disentigrate.  My Unis have wire inside frames so what you explain doesn't happen.   

It happens with UNI foam filters too, instead of being if chunks of foam, small particles of foam get into the fuel system.

Foam filters do nothing to improve performance unless they are part of a tuned system that includes a lot more than swapping a paper filter for foam.

K&N and Uni made millions selling this crap to the gullible.

[Triple Jim]

Excellent point - you can be almost certain that there are some chunks of foam filter in the oil.

I'd probably change the oil, but any rubber particles would have to get past the rings or valve guides to get into the oil, so I doubt if anything substantial made it in that direction.

[rodekyll]

I don't use them for a performance boost.  I use them to save space.  If you toss the huge airbox and use pod filters you have room for more stuff like a bigger battery or a tool kit.  In my particular case I had replaced the plastic forward piece of the EV's rear fender with an ATF tank for my Convert conversion.  Since it was a tank and not a flat bit, it extended into the airbox area.  So I binned the airbox and used pods.

[Arizona Wayne]

I use Uni foam for 2 reasons,  they allow more air to get to the carbs faster than a paper element and they better protect the motor in a sand storm, which I've ridden thru on occasion.  K&Ns I have no use for as they don't give near the air filtration foam does.  Many scooters come with reuseable foam air filters like my MP3s as do dirt bikes.

[Scud]

I use Uni foam for 2 reasons,  they allow more air to get to the carbs faster than a paper element and they better protect the motor in a sand storm, which I've ridden thru on occasion.  K&Ns I have no use for as they don't give near the air filtration foam does.  Many scooters come with reuseable foam air filters like my MP3s as do dirt bikes.

I use foam on my dirt bike - and it sees some seriously dirty air. Mostly they work great, but every now and then a certain oil and a certain foam are not happy together. I had one combo that disintegrated after two washings. I forget which filter, but it was the No-Toil oil (which has worked well for me with other filters). Now I try to use oil/filter of the same brand.

[Arizona Wayne]

I use foam on my dirt bike - and it sees some seriously dirty air. Mostly they work great, but every now and then a certain oil and a certain foam are not happy together. I had one combo that disintegrated after two washings. I forget which filter, but it was the No-Toil oil (which has worked well for me with other filters). Now I try to use oil/filter of the same brand.

I don't use just any oil....I use Uni foam filter & their tacky oil.  It takes very little of their oil at a time.  You just squirt a little on the pod, kneed it all over the foam, and it's done.  I've used the same oil bottle for years now.   Now it comes in a spray can.  I use the same oil on my scooter foam filters too.

[canuguzzi]

All good and fine if the engine can use more air which is rarely the case for most engines unless they are otherwise modded to include exhaust systems and such.

For reusability a foam filter might have an advantage, for better filtration, very doubtful.

A quality paper element filter generally gives the best performance in stock engines and flow more air than the engine can use. Both the exhaust and intake system must be properly tuned to work in conjunction with one another and in most cases people change to a foam filter and believe it filters better or flows more air, most often neither is true.

The idea that grit sticks to oiled foam better than being stopped by paper and other filter materials is fine in theory but often ends there, theory only.

Notice how many foam oil filters are all the rage? Me neither vut then some swear by toilet paper in a canister to filter oil too but at least it can work.

K&N and others finally pleated their foam filters after it was pointed out that once oil attracts grit it clogs the foams outer surface and flows zip.

Just how a metal screen of the types used on foam air filters keep out distintergrating foam particles must be the miracle engineering feat of the century.

You're far better off changing the air filter if it is paper than believing oiled foam does a better job.

If it works for you, great.

[NCAmother]

All good and fine if the engine can use more air which is rarely the case for most engines unless they are otherwise modded to include exhaust systems and such.

For reusability a foam filter might have an advantage, for better filtration, very doubtful.

A quality paper element filter generally gives the best performance in stock engines and flow more air than the engine can use. Both the exhaust and intake system must be properly tuned to work in conjunction with one another and in most cases people change to a foam filter and believe it filters better or flows more air, most often neither is true.

The idea that grit sticks to oiled foam better than being stopped by paper and other filter materials is fine in theory but often ends there, theory only.

Notice how many foam oil filters are all the rage? Me neither vut then some swear by toilet paper in a canister to filter oil too but at least it can work.

K&N and others finally pleated their foam filters after it was pointed out that once oil attracts grit it clogs the foams outer surface and flows zip.

Just how a metal screen of the types used on foam air filters keep out distintergrating foam particles must be the miracle engineering feat of the century.

You're far better off changing the air filter if it is paper than believing oiled foam does a better job.

If it works for you, great.

Ever since K+N started (in the auto industry) they've only used pleated mesh filters.  Maybe there is a foam K+N sock I don't know about?

[Arizona Wayne]

Ever since K+N started (in the auto industry) they've only used pleated mesh filters.  Maybe there is a foam K+N sock I don't know about?

Take your K&N and put it up to a light.............f rom the inside you can see light right thru the pleats. Now try that looking thru foam.

[Dukedesmo]

I know of similar incidents with Ducati 916/996 using an in-airbox foam filter, getting sucked into an intake and, due to the linkage/weak springs, jamming the throttles open, scary stuff if you suddenly get full power when you're trying to slow down.

ITG make a foam filter with a 'cage' inside to prevent this from happening, unfortunately neither design is good on a bike if it has a tendency to spit back unburnt fuel and/or flames.

Just below the fuel tank is not really the best place for a filter fire either... 

[leafman60]

I'm uncertain about what, if any, damage or threat was created for the engine. For rubber particles to get into the oil would be pretty amazing.

I'm more concerned about the rubber melting and clinging to the valves or maybe in the ring grooves of the piston.

I will probably change the oil anyway and then run a couple of bottles of Techron through the engine.  The engine ran very good afterwards to get me home.

[Triple Jim]

I wouldn't worry much about it melting and sticking to things.  The pieces that went through didn't have a lot of time to settle down on anything.

[Orange Guzzi]

I have a Buell Blast with a Mikuni 42 flat slide mounted and had a half round foam filter mounted.  Came back from a short ride and noticed the foam was missing.  The bike didn't miss a beat. 

I have started bikes with red shop rags and/or blue paper towels between the carb and valve.  They will suck right thru and come out in pieces or sparks if it is a red shop towel.  A good reason to be sober when working on a bike engine. 

[Triple Jim]

At least it isn't a 2-stroke engine.  Things are a little trickier when everything that goes through the carbs goes through the crankcase before it gets to the cylinders.  Foam rubber isn't too bad, but the road dirt that's trapped in it isn't good for crank bearings.

[krglorioso]

It happens with UNI foam filters too, instead of being if chunks of foam, small particles of foam get into the fuel system.

Foam filters do nothing to improve performance unless they are part of a tuned system that includes a lot more than swapping a paper filter for foam.

K&N and Uni made millions selling this crap to the gullible.

K&N filters are cloth over a wire mesh base.  The K&N air filter on my 2003 Suzuki SV-1000 now is 13 years old.  Other than clean and oil every few years it works just fine, as they do on my 2004 Buick LeSabre and 2004 Toyota Tundra.  As to foam filters, I have no faith in them for reasons noted above.

Ralph

[leafman60]

the road dirt that's trapped in it isn't good for crank bearings.

Yeah, I thought about that too. 

However, I had cleaned the filter less than a 1000 miles before this happened so not much dirt would have been there. 

Plus, I'm thinking any dirt would have been stuck to the rubber and hopefully burned discharged through the exhaust gases instead of clinging to the cylinder walls.

[rodekyll]

I have looked at the mesh in old K&N pods and seen bug-sized holes in the filter material.  They do deteriorate with age and should be inspected and replaced regularly -- just like any other air filter.

[leafman60]

K&N filters are cloth over a wire mesh base.  The K&N air filter on my 2003 Suzuki SV-1000 now is 13 years old.  Other than clean and oil every few years it works just fine, as they do on my 2004 Buick LeSabre and 2004 Toyota Tundra.  As to foam filters, I have no faith in them for reasons noted above.

Ralph

I've used K&N filters for years with no problems. Never had any noticeable wear problems either.

[cruzziguzzi]

I just can't warm up to those.

I know it was my own damn fault but I had a clean-and-oil set on my original Katana (one per pair) and somehow screwed up either cleaning or oiling them and set them on self-destruct.

What a frikken mess that was!


Todd.