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Author Topic: Smoking on start-up  (Read 3833 times)

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Offline TheBear

Re: Smoking on start-up
« Reply #20 on: December 13, 2015, 08:01:23 pm »
Unburned Fuel leaking past & landing up in Combustion Chamer?
White Smoke = Unburned Fuel
Blue Smoke = Oil
Just Saying

If that could happen easily with a Boxer,  I can only imagine how normal upright engines would billow smoke,  blue or white on every single startup.

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Offline Oshkosh

Re: Smoking on start-up
« Reply #21 on: December 14, 2015, 06:37:19 pm »
Unburned Fuel leaking past & landing up in Combustion Chamer?
White Smoke = Unburned Fuel
Blue Smoke = Oil
Just Saying

If that could happen easily with a Boxer,  I can only imagine how normal upright engines would billow smoke,  blue or white on every single startup.



Well I really can not compete in your engineering expertise so bow to your Un
-surmountable knowledge. :notworthy:
Just as a foot note.
Cold start up with auto choke/ecu software can give same effect of over fueling,  every machine is unique with there own trates just my observation over the years working with all types machinery.
Have fun cheers!  :thumleft:
« Last Edit: December 14, 2015, 06:45:16 pm by Oshkosh »
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Offline TheBear

Re: Smoking on start-up
« Reply #22 on: December 14, 2015, 06:55:04 pm »
Unburned Fuel leaking past & landing up in Combustion Chamer?
White Smoke = Unburned Fuel
Blue Smoke = Oil
Just Saying

If that could happen easily with a Boxer,  I can only imagine how normal upright engines would billow smoke,  blue or white on every single startup.



Well I really can not compete in your engineering expertise so bow to your Un
-surmountable knowledge. :notworthy:
Just as a foot note.
Cold start up with auto choke/ecu software can give same effect of over fueling,  every machine is unique with there own trates just my observation over the years working with all types machinery.
Have fun cheers!  :thumleft:

You look really cool bowing like that!   >:D

Please don't though.  I have no engineering knowledge, therefore I am asking the questions.  This particular one I have asked for some years now and still need to an answer, other than "well it happens".

.#BRADICAL!
 

Offline Tp007

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Re: Smoking on start-up
« Reply #23 on: December 16, 2015, 09:24:47 pm »
Unburned Fuel leaking past & landing up in Combustion Chamer?
White Smoke = Unburned Fuel
Blue Smoke = Oil
Just Saying

If that could happen easily with a Boxer,  I can only imagine how normal upright engines would billow smoke,  blue or white on every single startup.



Well I really can not compete in your engineering expertise so bow to your Un
-surmountable knowledge. :notworthy:
Just as a foot note.
Cold start up with auto choke/ecu software can give same effect of over fueling,  every machine is unique with there own trates just my observation over the years working with all types machinery.
Have fun cheers!  :thumleft:

You look really cool bowing like that!   >:D

Please don't though.  I have no engineering knowledge, therefore I am asking the questions.  This particular one I have asked for some years now and still need to an answer, other than "well it happens".


thanks, seems like it's a common thing and not something I should worry about. :thumleft:
 

Offline Flouw

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Re:
« Reply #24 on: December 17, 2015, 09:41:26 am »
Overfueling or choke on startup give black smoke. Too much fuel smokes black.

A little puff of smoke on startup isnt a bad thing.
Think about it, washing your bike without rinsing it first. All dry and scrapy and ruins the finish.

The oil collecting in the cylinder after switch off.
Rings have a gap. All 2 compression rings, and the oil scrapers. Although the gap is only 0.2mm(average estimate) thats big enough to let oil through. Thats when parked on side stand.
When on centre stand.
Well. The whole cylinder is coated in a oil filment. Thats what oil does....
Now the piston has stopped at the BDC(most bottom) all 70 odd mm of cylinder is exposed in all its glory to run and accumilate all oil at bottom of sleeve. Ons startup the oil is gathered up enough to burn and smoke a little.

Now with piston stopped at TDC(top, or closest to head then on boxer) the amount of open cylinder wall is minimal. And no collection of oil at the bottom.

On a upright motor. If oil seeps down cylinder. It collects on top of the piston. And/or seeps past the rings.

Now you get to valve stems. And seals. And the amount of oilyness in feul. Aswell as breather systems recircilating into intake boxes or intake manufolds.
Thats another very long post.
So ill leave that open to be asked 1st.
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Offline TheBear

Re: Smoking on start-up
« Reply #25 on: December 17, 2015, 05:55:25 pm »
Okay!   An explanation I think I understand.  

So,  basically,  if I understood correctly,  it makes no difference whether a Boxer or upright engine on side stand or centre stand.   Sooner or later,  a bit of oil will seep past and cause a puff of smoke? Said puff of smoke is no indication of harm done?   It must be less likely on an upright though.

If that,  it is what I always thought.   Didn't understand the mechanics,  but understood the concerns even less.
« Last Edit: December 17, 2015, 05:59:57 pm by TheBear »
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Offline ChrisL - DUSTRIDERS

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Re: Smoking on start-up
« Reply #26 on: December 17, 2015, 05:59:02 pm »
Said puff of smoke is no indication of harm done?

No harm done, but it mostly happens when you have an audience and then it's not lekke :eek7:
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Offline TheBear

Re: Smoking on start-up
« Reply #27 on: December 18, 2015, 06:31:52 am »


No harm done, but it mostly happens when you have an audience and then it's not lekke :eek7:

Haha!   No man,  I have (THANKFULLY)  reached an age where the audience doesn't bug me anymore.
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Offline Clint_G

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Re: Smoking on start-up
« Reply #28 on: December 18, 2015, 07:41:50 am »
You guys are missing the actual cause of the problem. Your bikes are standing for too long if they have time to seep oil past the rings. Ride the bloody things.  :peepwall:  :ricky:
 

Offline m0lt3n

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Re: Smoking on start-up
« Reply #29 on: December 18, 2015, 07:46:27 am »
not much to add except this sounds like the same I have on my air cooled. it happens more in cold weather but is very temperamental and will sometimes not happen in the worst of conditions and other times I will see smoke on a warm morning while bike was on centre stand. I have also made peace with it
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Offline Flouw

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Re:
« Reply #30 on: December 18, 2015, 08:20:13 am »
Air cooled ones are worse, as piston to bore clearances run quite a bit bigger.

Now, on the flip side of things.
Dont ignore it completely.

Now we get to the other cause.
Valve train wear, valve guides and seals.
If the valve stems or guides are worn. The valves will start rocking away and eat the seal out. And when switched off, oil wil seep past the stem and settle on the valve head and seat on port side. Once you crank the motor that oil will then get sucked through to combustion side. And gooi a leker puff on startup. This is on flat and upright motors.
Old hardened seals will do the same even if the guides and valves are perfect.
The easiest test that indicates this. While riding. On the higher end of the RPM. Close throttle and let the bike "brake" itself in gear for RPM to get down. And when you jab the throttle again, a leke puff of white/blue smoke.

Thats the 101 for the day.
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Offline TheBear

Re: Smoking on start-up
« Reply #31 on: December 18, 2015, 11:45:57 am »
You guys are missing the actual cause of the problem. Your bikes are standing for too long if they have time to seep oil past the rings. Ride the bloody things.  :peepwall:  :ricky:

True!

Then, some okes are so filled with fear due to these stories, they centre stand their boxers for a smoke break!

Air cooled ones are worse, as piston to bore clearances run quite a bit bigger.

Now, on the flip side of things.
Dont ignore it completely.

Now we get to the other cause.
Valve train wear, valve guides and seals.

THis reminds me of the older 3.0V6 Ford engines.  They rolled out of the factories with leaking vale stem seals and guides ...
« Last Edit: December 18, 2015, 11:47:11 am by TheBear »
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Offline Flouw

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Re: Re: Smoking on start-up
« Reply #32 on: December 18, 2015, 01:44:26 pm »
You guys are missing the actual cause of the problem. Your bikes are standing for too long if they have time to seep oil past the rings. Ride the bloody things.  :peepwall:  :ricky:

True!

Then, some okes are so filled with fear due to these stories, they centre stand their boxers for a smoke break!

Air cooled ones are worse, as piston to bore clearances run quite a bit bigger.

Now, on the flip side of things.
Dont ignore it completely.

Now we get to the other cause.
Valve train wear, valve guides and seals.

THis reminds me of the older 3.0V6 Ford engines.  They rolled out of the factories with leaking vale stem seals and guides ...
Can tell me nothing about the old fords....
The cast iron heads with guides and valve was/is a major wear issue. Thats why they made them only half seal so lubricate the valves and guides.
At this stage on the race car i assemble the head without seals. I can afford a little smoke on startup, but rebuilding heads all the time is getting expensive. And scarce. And porting in insanely labour intensive
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Offline Ouman

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Re: Smoking on start-up
« Reply #33 on: December 18, 2015, 02:10:41 pm »
O jong! Ek rook so bietjie as ek te te lank sleef staan!  :lol8:
The more bugs in the  teeth....the happier I get!!!!!