Exhaust Infestation?

I am fairly certain that my experience was a rare one, but others may take a lesson.  Recently I took out my '13 GRiSO for its inaugural ride this season (I had been neglecting her in the garage for a bit).  I decided to pass my wife on her bike, which then resulted in a "Martin, something is burning on your exhaust!" report loudly coming in on the Bluetooth communicator.  

My immediate thoughts were perhaps something was burning on the exhaust (maybe my saddlebag, maybe some residue from a spill?), or perhaps there is an unusual amount of exhaust and the bike was running rich?  I quickly pulled over to the side of the road, killed the ignition and jumped off the bike. Nothing was touching the stock exhaust, but sure enough smoke was billowing out.  Not a little smoke, a lot of smoke. I should have recorded it on my phone, but I was more than a little surprised, and trying to process how this was happening. Oddly, it smelled like a campfire with maybe a hint of popcorn and not the pleasant smell of oil rich gas exhaust.

We waited for the smoke to dissipate, and I peered in the still smouldering exhaust pipe. Nothing, I could see nothing. I found a twig to poke in and see if it could find an obstruction, nothing. After a few minutes of head scratching, I decided the best course would be to turn around and limp the 4 or so KM back home to my garage. I rode gingerly, pulled into the garage, and shut the bike down. There was still smoke emanating, although more wispy than billowy now. I did record a video, and noted that it still smelled of burnt popcorn. What the hell?

I recalled that I recently emptied the garbage bins and saw a small creature had chewed through some bags in my bear proof bin and there were popcorn kernels on the bottom of the bin beside the garage.  Had a mouse stashed a good supply of popcorn kernels in my exhaust?!  I have heard tell of seeds and other debris stashed by squirrels or birds in snowmobile air boxes, but I had never imagined a mouse or other critter could find their way into a bike's exhaust.

I decided to quickly take off the exhaust and inspect. I managed to only burn one fingertip in the removal process. This mystery could not wait for the bike to cool down. With gloved hands I shook the still warm, now removed and oversized can. Nothing was escaping the baffles, but I could definitely hear a rattle, I assumed this was not normal. Do exhaust cans sound like maracas when shaken normally? Doubtful.  

I started the now exhaust-less GRiSO, just to confirm that nothing would smoke out from deeper within the bike. There was a fantastic roar from the newly un-muzzled beast, but thankfully no flames or smoke.

The mysterious smoke does seem to have been caused by a cache of corn kernels. With some shaking and twisting I can get a few
pieces to escape the canister, but whatever the internal construction of the stock exhaust is, (from the weight I am guessing it is made with cast iron) it seems to hold popcorn kernels in fairly securely. I imagine there may be a cremated mouse rattling in their too. I am tempted to cut it in a cross section.

Long story short, I have finally ordered the aftermarket exhaust long desired and needed. Looks like I will need to purchase a map for the Agostini HF now on route from Texas to northern Canada from Mr. Beetle. This experience was a bit baffling, but I do wonder how common it might be?

Was the bike running OK? Not feeling weak and gutless?

Pete Roper wrote:

Was the bike running OK? Not feeling weak and gutless?

probably just popping on the over run....

Papa Lazarou wrote:

Pete Roper wrote:

Was the bike running OK? Not feeling weak and gutless?

probably just popping on the over run....

Boom, tish!

Well, it makes for a good story. Not bad for your first post, mgoldney. Welcome to the Ghetto!

Pete (Street)

The reason for my question was that if the engine was feeling weak or pulling poorly I'd be taking a good hard look at the plug caps as a possible cause for smoke and heat from the 'Zorst.

Pre-processed E85

Thanks all. It was the first ride on the GRiSO in many months, but I did not notice a loss of power and she didn't feel gutless. The ride was short though. Not sure how much smoke that would generate. There was a lot of smoke. There was enough smoke that there could have been a conclave of bishops electing a new pope in there. I know this seems implausible and perhaps there is another contributing factor. Will take a look at the plug caps nevertheless.

Check out this video I shot a few years ago of my friend Martin making popcorn in his glassblowing studio.

Found the video I took in the garage. The initial smoke event was much much larger. [You must be registered and logged in to see this image.]

I was going to guess wasp nest, until you mentioned getting some of the kernels out.  Probably a little inception given the thread title.  [You must be registered and logged in to see this image.]  But like you, I don't know how the stock internals are configured I had in mind the aftermarket db killer/internal tube layout that could capture some organics.

Good one, congrats on finding such solid rationalization for the upgrade that you wanted to do anyway.
[You must be registered and logged in to see this image.]

And I'll be darned if I wasn't just, over the weekend, reading about the houseboats and the shack community up there, and commisserating about estimated 50+ hour theoretical transit to/from with an ADV friend of mine, haha.

Hi, out of the whole story I did not see if you tried to pull the exhaust can apart? It breaks down quite simply and easy with just a screwdriver, no overengineering in there.
Cheers

My mother had a 750 Virago many years ago that a squirrel stuffed acorns in the exhaust. When we started it up after taking out of storage one year, the acorns were shooting out like bullets with every rev. Many got lodged in the drywall in the garage. It was hilarious!

evev wrote:

Hi, out of the whole story I did not see if you tried to pull the exhaust can apart? It breaks down quite simply and easy with just a screwdriver, no overengineering in there.
Cheers

No glass fibre, right? Just steel chambers?

No glass fibres in there, not that I found. Couldn't find the picture of that whole thing laying out piece by piece. (Had to do major overhaul after one valve burnt out...)

Most OEM Silencers are the Multi-Chamber type.
They're cheap to produce, pretty effective, and there's nothing to degrade (no Fibreglass Wadding for instance), other than the metal itself.

[You must be registered and logged in to see this image.]

evev wrote:

Hi, out of the whole story I did not see if you tried to pull the exhaust can apart? It breaks down quite simply and easy with just a screwdriver, no overengineering in there.
Cheers

Thanks, I will take another look at pulling the exhaust apart. I got the end cap off but ventured no further. The aftermarket exhaust will be here soon so the OEM will be completely sacrificial. If I can't manage to disect it with a screw driver, a reciprocating saw should work.

Lehctim wrote:

My mother had a 750 Virago many years ago that a squirrel stuffed acorns in the exhaust. When we started it up after taking out of storage one year, the acorns were shooting out like bullets with every rev. Many got lodged in the drywall in the garage. It was hilarious!

Haha.  I shared my story with a cousin. He told me his dad always advised putting steel wool in exhaust pipes for equipment stored outside to prevent rodent intruders. Guess it is more common  than I originally thought.