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black smoke

Discussion in 'Technical and Troubleshooting Torque' at netrider.net.au started by kungfupigeon, Jan 25, 2010.

  1. hey guys, riding a 98 Suzuki Across - GSX250F...

    Noticed today that when i rev my engine some black smoke occassionally shoots out of the muffler... just wondering what are the common causes of black smoke so i can take a look at them? thanks.


     
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  2. Mine did the same thing today when I revved it in neutral.. just having fun :)

    If you hold the revs up around 3/4 of the way, back off and then rev it again really fast you may see a little puff of smoke come out.
    The vacuum caused when backing off can sometimes suck oil through the valvestems which burns in the mixture.

    Very common and can happen even in a perfectly good motor. Nothing to worry about


    If you get a constant stream of smoke during idle, or under power it may be worth looking into


    -
    Chris
     
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  3. Black smoke usually is a sign of rich running or a huge fuel dump. You gave your across a huge fuel dump when revving it.
    Nothing to worry about.
     
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  4. Yeah that (y)

    My bad, confused black smoke with white smoke.. I'll get it right eventually ](*,)
     
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  5. *wipes away sweat drop* i was genuinely worried.... now im not. thanks guys
     
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  6. Remain worried, you ride an Across. 8-[
     
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  7. Come on now, just because he rides a handbag on wheels doesn't mean theres any need to be mean :angel:
     
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  8. *testicles shrink*
     
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  9. Haha, dont worry.. If anyone asks just say you're borrowing your hot girlfriends bike while yours is in the shop :p

    And its still a bike, so girls will be still be impressed


    -
    Chris
     
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  10. Same thing happens to my GS850, and my KV100, and my car, and...and...and...

    Yeah, you got it. Its perfectly normal for carburetted vehicles.

    Interestingly, the valve-leakage that Cypher described in the second post is partially what made earlier Ferrari's so revable. Their valve guides were made of bronze and wore quickly, thus introducing oil into the cylinder at higher rpms. This made them forgiving to amateur race drivers and all let them be rev to the bejesus.

    Cheers - boingk
     
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  11. Black smoke: Fuel
    Blue smoke: Oil
    White smoke: Coolant getting into combustion chambered (eg head gasket).
     
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  12. :rofl:
    anyway OP, just to be thorough... just a single puff? or a stream of black smoke at high revs? How long since service?
    If it's a puff, don't worry about it. If it keeps coming out in a steady stream (usually at high revs) the valve clearances might need checking. Not a big job, but closed up exhaust valves will burn out fairly quickly, and then it gets messy.
     
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  13. PMSL...don't forget to include all Honda's in that analogy

    Back on topic....black (sooty) smoke = excessive fuel ( rich )
     
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  14. thanks for the replies.. jsut a puff... noticed there is no black smoke now that im running on 95 ethanol as opposed to v power XP
     
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  15. Couldn't have said it better myself.(y)
     
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  16. DON'T use ethanol fuel!!!!!
    Your lines will start to crack and the fuel can 'gunk' up if left sitting for too long.
     
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  17. Thats a fairly simple way of putting it, however I can never see any blue in oil smoke.
    My car got a 2nd hand replacement engine which I got for free - found to have leaky valve stems and smoked like a biatch on idle (especially the first little rev AFTER idling..) but never noticable when moving.
    It burnt through maybe 1-1.5L of oil in under 2 weeks.. and only had white smoke

    There's only been one occasion I've seen it actually blue and that was when a GD35 (I think) Garret Turbo was stuffed, but using the same base engine that I had.
    Perhaps different types of oil..? synthetic vs mineral?

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    Chris
     
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