smokes on cold start- why?

[ny300exrider]

ive always wondered what is the actual reason for engines to smoke when started if its cold out. im thinking it may have to do sometihng like how you see your breath but i never really knew what the real cause of this is. if anyone wants to shed their intellectual side thatd be great.

thanks

[Jersey450R]

The condensation in the pipe

[Pappy]

possibly the extra fuel being burnt from using the choke

[FasstMidnightZ]

thats what i heard form the extra fuel buring from the choke ive also heard that its from the oil being cold but know how

[JDiablo]

its the oil on the piston or rings i forgot,and when you start it off it burns cause its not hot enough,therfore when it gets hotter it doesnt smoke....ehh doesnt sound to bad

[speedy400]

ep, bolth^ are right,
Because the motor is cold, the fuel dosnt atomize in the intake ports like it would when its warm, so the trick is to send less air and more fuel so theres more of a chance for the fuel to disperce and ignite(fuel dosnt burn well when its liquid form..) so when you start it up theres a little bit extra fuel not fully being burnt, but it does eventually get atomised after it leaves the combustion chamber inside the pipe because it has much more of a chance(pipe is much longer in length than the ports.) So the result is you have some "smoke" aka atomised, unburned gas.
Also like when you boil water, steam comes off, condencation forms in your pipe/ and such and it ends up steaming out(also smoke).


FYI-
blue smoke-burnt oil
black smoke-1/2 burnt gas- also a sign of being very rich jetting if it continues
white smoke- steam-water

I'm not absolutly positive, but this is what I have learned.-darren

[speedy400]

Originally posted by 300exrida
its the oil on the piston or rings i forgot,and when you start it off it burns cause its not hot enough,therfore when it gets hotter it doesnt smoke....ehh doesnt sound to bad

yeah.. kinda, when the rings are cold they are somewhat smaller then they are suppose to be ( they sould be perfect when the motor is hot...rings expand because of the heat) so when its cold the oil being splashed up from the bottom end, some gets past, and the oil burns and shoots a little blue smoke out.. then when it warms up it'll stop, unless you have bad rings that are worn out, it'll always let a little oil past.-darren