Pod Air Filters

[2LZ]

At one time, I didn't think twice about gutting an airbox out of a bike and putting on an Uni pod filter. They're cleanable, filter better, are cheap and sound cool. I had two Uni pods on my two Hensim 150's. A friend and I were out riding at our local OHV park and were climbing a not-to-steep hill. I popped over the table top, looked back and I didn't see him. I looked over the hill and he had killed it about 3/4 of the way up. Apparently a little fuel had run back into the pod from being on the hill and in an attempt to kickstart, it popped back through the carb and the Uni all but burst into flames. Within less than 20 seconds, the flames had engulfed the gas tank. Seriously, it lit off very similar to a burning ping pong ball. I finally swatted the now-gooey burning filter off the carb onto the ground, of course causing some pretty good burns to my hand that the melting filter stuck to. (I had left my gloves with my bike)

Anyway, my Hensim escaped rather unscathed but wow....I'm not to sure about hanging a little seriously flammable foam pod right off the carb now. I still have one on my X-Moto but after that, I attached some radiator hose to the carb and spaced the pod back about 10".

I've been looking at the K&N-style filters. They seem like they may not be quite as flammable. Anyone using these? How do you like them?

[Adjuster]

Interesting. I don't think I want my pod filter to become an inflamed gooey mess right between my legs.



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[Weldangrind]

I've tried the fake K&N filters, but I struggled to get them to breathe, even after oiling them very lightly. IMHO, the Uni pod style is better in fine dirt and sand.

[Jay In Milpitas]

Any pod type filter can become a torch once fuel gets in it. Being out in the open air increases the risk.

A closed filter chamber tends to suffocate any backfire induced fire, that's why you seldom hear of one burning to the ground.

There is also the factor of pulse tuning the inlet tract that pods don't provide. That's a full treatise in itself so I won't expand on that here.

Basically, if you can make a chamber to enclose your pod type filter, you can also route an inlet from a location that is less likely to draw dirt. Back in Ye Oeld Dayes before unitized engine/gearboxes and when shift levers & patterns were all over the compass, we used to prepare for dusty/silt rides by smearing the inside of the air filter box with grease. As the air flowed in, inertia made much of the dust/silt go against the wall and get trapped in the goo.

You don't get the peachy keen intake sound, but that's the price you pay.

Then again, there WERE bikes that just had wire mesh screen to keep out gravel and small birds. Flogged them until the rings wore and the exhaust was faded denim blue, then just honed and put in new rings.

[FastDoc]

Glad it turned out OK.

Another thing to watch for with pod filters is that they don't tear where the soft foam meets the plastic mounting base. Could be hard to spot if you are not looking and the dirt entrance would be lousy for the engine.

Were you at Metcalf? I used to ride there often when I worked at Stanford. Nice little place and great location. Glad to hear the Greenies didn't shut it down.

[2LZ]

Originally Posted by FastDoc

Glad it turned out OK.

Another thing to watch for with pod filters is that they don't tear where the soft foam meets the plastic mounting base. Could be hard to spot if you are not looking and the dirt entrance would be lousy for the engine.

Were you at Metcalf? I used to ride there often when I worked at Stanford. Nice little place and great location. Glad to hear the Greenies didn't shut it down.

We were out at Prairie City (used to be McGill's before the state took it over). It's where they've had the Hangtown Classic for years now since it left Placerville.
It was just an odd set of circumstances, probably amplified by the fact my buddy just learned how to ride. I've been running Uni's for decades, my Husky still has one in the original airbox as does my X-Moto. It's just out of 57 motorcycles and 48 years of riding....I've never had one go up in flames like that! It was incredible how fast it spread and how tall the flames got. If you ever have to toss an old one, light it for the entertainment factor.

[FastDoc]

LOL!

Any good man appreciates a good fire.

[SpudRider]

Originally Posted by 2LZ

...If you ever have to toss an old one, light it for the entertainment factor.