Air Filter Caught Fire

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Tornado

Tornado

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Was spraying a bit of brake cleaner around the intake manifold to check for leaks. Put a few squirts on HamCan grill to check what effect on idle would be. Found it dropped idle a fair bit. After shutting down for a few minutes, noticed the filter glowing orange beneath the grill! Pretty scary. Got it put out with windex sprayer.

Where did it ignite from?
 
Please I hope you have pictures!
Seriously, thankfully, sounds like you caught it before major damage.
No idea what caused it.
 
Will take apart shortly and take some snaps if anything worth sharing.

I can only think of "backfire" flame coming from carb but seems remote, no?
 
Check the wires from the alternator and any others routed below the air box. I discovered a fractured horn wire on the '69 S that looked like it probably had worn through the insulation by vibration on the rear airbox plate or the battery tray.
 
I wouldn't use brake clean to check for intake leaks... I use carb cleaner instead. Needless to say various fluids have different solvents and propellent chemicals in them. The fluid which most often in my experience ignites in the intake is starting fluid because it has such a low temperature flash point and high flame propogation speed. It doesn't take much to start a fire in the intake of an engine using starting fluid. Perhaps that is true of brake clean fluid too. That would explain why it ignited. The vapor from it ignites and the intake valve doesn't close fast enough because of the the speed of the ignited vapor of that particular fluid. (or something like that)

I've had many a lawn mower with an intake on fire from using starting fluid, and a few cars too.
 
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Here's the aftermath pic:

Air Filter Caught Fire

Air Filter Caught Fire


Looks like upper right side got most of the brunt.

I've tossed an old filter in for now...not sure history of it as got it from a seller with box of used parts. Will order a fresh-un or might split for a K&N type made for the hamcan.
 
concours said:
A PROPER (designed) air filter element contains wire mesh on the inside, which acts as a flame arrester.
Click to expand...
That there sounds like a good reason to go for the K&N NO-0100 hamcan model filter. Looks like upwards of $90 here in Canada.
 
K&n will last as long as you own bike , just keep it clean and try not to burn it
 
deleted.
Edit: no I got to say something. Really!
Did the can of Brake Clean have a flammable symbol on it? Now you are blaming the Ham Can Paper Filter?

Here is what is written on my Blaster Brake cleaner:
Contents harmful
Contents May Catch Fire.
Container May Explode if heated.
and another one:

Emzone Brake and Parts cleaner:
Extremely Flammable aerosol.
Switching to a different K&N doesn't fix that maneuver. IMHO
 
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Did I blame anything?
Does starting fluid also have a flammability warning on it and don't folks spray that into filters as standard procedure?
 
Consider the possibility that "spitback" or standoff as it's more commonly referred to may have deposited some fuel on the filter medium and spraying the brake cleaner momentarily gagged the engine causing a slight backfire that ignited the fuel-sodden paper.
 
Brake cleaner has a very high solvent content cos it’s designed to evaporate off and leave zero residue behind on your brake surfaces. It could just have been the heat that caused it to ignite.

You’re a lucky man!
 
Starting fluid washes the oil off the cylinder walls which is not good. It is not meant to be sprayed on an air filter.

Have used the K&N element. It is slightly too thick and makes it harder to get the air cleaner together. I went back to the paper element.
 
Tornado said:
Did I blame anything?
Click to expand...
Tornado,
Sorry but this is what I got out from this thread ("That there sounds like a good reason to go for the hamcan model filter.") Which in my opinion would not changed anything.
I was sarcastic, possibly. But go back to post #5 by o0norton0o. He worded it more politely than I. But good move to hit the embers with something and that you got a early fire below your fuel tank under control. You were lucky. Hopefully this turns out to be a Lessons learned event.
Cheers,
Tom
 
Tornado said:
Will take apart shortly and take some snaps if anything worth sharing.

I can only think of "backfire" flame coming from carb but seems remote, no?
Click to expand...

Not at all remote. My buddy had a foam reusable filter way back that caught fire when starting the bike. Burnt his 72 Combat to the ground before the fire truck could get there. I had the same filter on my 850 that caught fire and like you I had some water handy. These memories make me leery of oil soaked air cleaners.
 
Please tell me it was not a Uni-sock style filter , that burned the Combat to the ground ....
 
My first bike was a BSA 650 that used to spit back while trying to start it. More than once I had open flames emanating from the carb mouths. I learned pretty quickly that I just had to kick it over and it would suck the flames in and snuff them out. Your event was certainly different. For one thing, I didn't have any air filters, and your fire was on a running engine. I'm glad the windex bottle rescued the bike!
 
Just a couple more cents...propane is good for testing for manifold leaks. Use a torch that allows you to turn on the propane without igniting it and then pass the nozzle around the manifold. It's easy and clean and engines run well on it. Brake cleaner is flammable but not intended as fuel for a combustion engine. Big difference.

The engine will speed up when the propane is ingested, which does not tend to cause a backfire like bogging it.
 
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