Assistance with a Minor Mystery - Black Substance on R1200RT Wheel

[exgman]

Well, for the first time in a month, I took my RT for a little ride yesterday. FWIW, it has been sitting in my NJ garage since late December. I wheeled it out, fired it up, andsaw the tire pressures were good. Then I looked at the rear wheel, and saw something odd...a black liquid had seemingly leaked from somewhere on the bike, dribbled down one leg/spindle of the rear wheel and dried there.

I made some photos of the wheel, and also used a couple of paper towels to wipe the stuff off the wheel. It seems grainy, and has no smell. it's not greasy but granular and very black.

A short ride on the bike showed normal behavior. Brakes worked fine, no warnings, just normalcy. I'd appreciate ideas about what this might be. FWIW, the bike has performed flawlessly for 40,000 miles. Thank you for looking and your ideas about this. JG

Photos:

 

[r0ckrat]

Well, for the first time in a month, I took my RT for a little ride yesterday. FWIW, it has been sitting in my NJ garage since late December. I wheeled it out, fired it up, andsaw the tire pressures were good. Then I looked at the rear wheel, and saw something odd...a black liquid had seemingly leaked from somewhere on the bike, dribbled down one leg/spindle of the rear wheel and dried there.

Did you wash the bike just before parking it last time? My guess would be a little brake dust mixed in some water that rolled down from the caliper/hub after parking it.

 

[lee]

Cat piss?

 

[akbeemer]

Bat guano…..

 

[Omega Man]

I would put a few drops of water on the stain and see if it’s water soluble. I have also seen this kind of substance/stain come from the exhaust when there is a cold meets hot condensation liquifies a bit of carbon from the exhaust. Water that happen to get into an exhaust during a wash can do it as well.
OM

 

[54571]

Cat piss?

Lmao


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[ahd43]

Wouldn't cat piss melt the paint? Ima going with brake dust juice.

 

[exgman]

Ah well, I'm glad to have provided a little occasion for humor. First - thanks for helping with my minor problem. I'll wipe off the black stuff, and ride on. See you all in MO I hope; Second - No cats and no bats in my garage.

I hope everyone has a fine weekend. Predicted 65F here in South Jersey, so you know what I'll be doing.

JG

 

[ahd43]

Have fun! Lots of salt on the roads here is PA Central. I'll wait.

 

[akbeemer]

Ah well, I'm glad to have provided a little occasion for humor. First - thanks for helping with my minor problem. I'll wipe off the black stuff, and ride on. See you all in MO I hope; Second - No cats and no bats in my garage.

I hope everyone has a fine weekend. Predicted 65F here in South Jersey, so you know what I'll be doing.

JG

Hmmm, you live in Jersey, so I’m guessing you’re doing your taxes.

Many of my family lived in Jersey.

 

[lee]

Wouldn't cat piss melt the paint? Ima going with brake dust juice.

We used to have a cat that hung out at our house and if I harassed it too much it would spray my K75S black engine.
It liked Debbie and never sprayed her bike.
It never hurt the engine paint but cat piss does not smell good when the engine gets hot.

 

[lee]

Ah well, I'm glad to have provided a little occasion for humor.

JG

I was serious about a stray cat getting to your bike.
The spot at the TPS sticker looks too thin for gear oil and the exhaust would not drip there.
The spot appear to have happened while the bike sat.
If you had a leak during the last ride you would see rotation streaks.

 

[Moretti]

It depends…

My (lay) understanding is that ectoplasm, though typically transparent on initial expression, discolors after a period of time due to such factors as the air quality index, room temperature, substrate composition, etc.

 

[exgman]

I was serious about a stray cat getting to your bike.
The spot at the TPS sticker looks too thin for gear oil and the exhaust would not drip there.
The spot appear to have happened while the bike sat.
If you had a leak during the last ride you would see rotation streaks.

Thanks Lee. I've got an enclosed garage, to which no cats have access. I'm tending to think that the location which seems to indicate some sort of dark liquid flowing down the wheel spindle(?) is probably detritus which came off the rear brake following a wash. My increasingly porous mind vaguely recalls a P21S wash back in mid-December following a ride. Maybe that was the result? Otherwise, the bike looks pretty clean, so I'll buy into that theory.

 

[rangerreece]

John

I’ve had that on my bike, it’s no big deal. It’s break dust and liquid, moisture/condensation. I’ve seen it on Gretchen. Sometimes my garage floor is coated in condensation, meaning, my rims are covered in condensation. When it’s thick enough to form full droplets, it rolls down the rim consolidating near the bottom, picking up break dust along the way. When it dries, it forms that dry black chalky texture.

 

[lee]

I’ve had that on my bike, it’s no big deal. It’s break dust and liquid, moisture/condensation. I’ve seen it on Gretchen. Sometimes my garage floor is coated in condensation, meaning, my rims are covered in condensation. When it’s thick enough to form full droplets, it rolls down the rim consolidating near the bottom, picking up break dust along the way. When it dries, it forms that dry black chalky texture.

Our first house was like that. When it was cold and the humidity was high the floor would get completely wet and the car and bikes would have enough moisture sometimes to drip.
Thankfully our present garage does not have that problem.