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Author Topic: Brown smoke?  (Read 1195 times)

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Offline Lostboy Steve

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Brown smoke?
« on: August 22, 2011, 08:30:29 AM »
I know I know no such thing. Seriously this is the first time I've really let the engine get hot. It was running fine but when I rev it a good amount of brown colored smoke comes out of the left pipe only. The right is clean. Could it be old #$%* that has collected in the newly coated pipes that became loose during the baking process? I haven't synced my carbs yet but again it's not fuel, and it's not oil. Very strange... The carbs seem tremendously out of adjustment (hanging idle and terrible throttle response) but it starts one kick without choke and idles smoothly if the throttle isn't moved. It's gotta be some internal rust and carbon right?


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1977 Honda CB550K
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KingCustomCycles.com

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Re: Brown smoke?
« Reply #1 on: August 22, 2011, 08:35:12 AM »
unburnt fuel, carbon, rust off the inside of the pipes.  I bet if you held a white sheet behind it while you revved it would catch the particles.  I have had them so bad I had to sweep the garage after a short run.
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Offline Rgconner

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Re: Brown smoke?
« Reply #2 on: August 22, 2011, 09:12:02 AM »
Cheech Marin the PO?
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Offline my78k

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Re: Brown smoke?
« Reply #3 on: August 22, 2011, 09:14:16 AM »
check the carbs for air leaks around the boots. Spray some wd40 around them and see if the idle changes.

Won't have anything to do with the brown smoke but might solve (or at least improve your idle issues)

Dennis
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bollingball

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Re: Brown smoke?
« Reply #4 on: August 22, 2011, 09:32:14 AM »
Let er rip burn it off. Then fix your carbs ;)
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Offline TwoTired

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Re: Brown smoke?
« Reply #5 on: August 22, 2011, 10:08:29 AM »
Maybe you are scaring the #$%* out your bike? (Running it out of proper tune.)

Could be raw gas burning in the pipes of the weak cylinders.  ???
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Lloyd... (SOHC4 #11 Original Mail List)
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Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Lostboy Steve

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Brown smoke?
« Reply #6 on: August 22, 2011, 10:20:46 AM »
It's not raw gas. I just rebuilt the carbs I just haven't dialed them in yet. I'm not "running it" I just ran it enough to get hot to make sure there were no oil leaks or anything. Again brown smoke is not gas black smoke is. I think king is right it's due to pipes that have been sitting for 20+ years.


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2018 Indian Scout

bollingball

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Re: Brown smoke?
« Reply #7 on: August 22, 2011, 10:47:48 AM »
Well if you have not dialed them in it could be gas. I say get it up to temp good and hot then you burn oil and paint or what ever off. Then look at the color if there is any. IMHO
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Offline TwoTired

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Re: Brown smoke?
« Reply #8 on: August 22, 2011, 11:57:01 AM »
Quote from: twistedengineering on August 22, 2011, 10:20:46 AM
Again brown smoke is not gas black smoke is.
I didn't say the smoke was raw gas (which would be white).  What I'm saying is that raw gas is maybe lighting off inside the pipe and burning something inside the pipes.
What is burning is maybe something you want to keep in the pipes, like a coating.

Further, take a look at some color charts,  Just like black is a component of grey, it can also be a component of brown.  Black in exhaust is unburnt hydrocarbons, and is different from raw gas in atomized form.

Unless, of course, you live in a black and white world.  ::)

Fix your carbs.

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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

KingCustomCycles.com

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Re: Brown smoke?
« Reply #9 on: August 22, 2011, 12:24:02 PM »
"and get out of my yard" :-)
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