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Flipped bike and now it's dumping smoke out exhaust?

By bbohannon,
in 250/350/450/505 SX-F & XC-F

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bbohannon

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I wrecked pretty good this weekend and the bike flipped a couple times.  I was on the side of the track injured for quite some time and paid no attention to the bike.  The bike doesn't have any obvious bends/breaks but it now has substantial amount of white smoke out of the exhaust.  The bike starts up fine (haven't ridden it yet).  I do have a rekluse but I'm unsure if the bike was running while it was on its side and I was hurt on the side of the track.

 

I'm afraid to ride the bike for fear of further damage.  The bike is not low on oil or coolant.  What are the possibilities of damage and what should I do next?

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Kevin Reynolds

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I would say determine if the smoke is coolant or oil smoke. If its coolant I don't have a suggestion. If its oil and the bike was upside down for an extended period of time, I would pull the breather tube and see if you had oil flowing through it. I don't know what bike you have, but if the breather routes to the air box it may be sucking that oil into the intake..

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bbohannon

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I would say determine if the smoke is coolant or oil smoke. If its coolant I don't have a suggestion. If its oil and the bike was upside down for an extended period of time, I would pull the breather tube and see if you had oil flowing through it. I don't know what bike you have, but if the breather routes to the air box it may be sucking that oil into the intake..

Good suggestion.  I have a 2009 250 XC-F.  I'm not completely certain where the breather tube routes to but will look to see if it goes to the airbox.

 

If this happened, what is worst case scenario?  Do you believe there would be any damage involved? 

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Kevin Reynolds

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Good suggestion. I have a 2009 250 XC-F. I'm not completely certain where the breather tube routes to but will look to see if it goes to the airbox.

If this happened, what is worst case scenario? Do you believe there would be any damage involved?

Well I'd say you might get some, if any carbon build up on the piston dome, cylinder head, valves and exhaust valve stems. Damage? If in fact your breather hose from the valve cover did in fact fill with oil and it is connect to the air box or intake I would pull the hose and flush it out and clean everything the oil passed thru (air box, intake, etc). Any oil left in the cylinder should be flushed out with fuel from the carb and burned off once its running.. You may want to change the spark plug as the plug in it now may be fouled even though it still runs.. Then change the plug or clean it again after it stops smoking.. Unless you were really hauling ass and when you crashed the bikes RPM was to the moon and was forced into an abrupt stop like someone stuck a crowbar in your sprocket while at 12k rpm, I don't see where and damage could have been done!

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tye1138

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Hmm... I mean the first thing I'd do is a compression test, followed closely by making sure there isn't any built-up pressure in the radiator.

When discussing 4 strokes, the only real way water can get into the combustion chamber is through a cracked cylinder or bad head gasket. Both of those things can be determined through the test I propose.

Oil isn't going to magically get in the combustion chamber unless your rings or valve guides have failed. I highly, highly, highly doubt that would have happened. Heck, even a water pump failure, which puts coolant into the crank case, would be noticeable in the radiator coolant level and wouldn't effect the combustion chamber until the crankcase was full of water. The crankcase breather isn't an issue, no way.

At first thought, I think it over heated whilst it was on its side and that caused the head gasket to leak slightly. I can't imagine anything else that could have happened. I don't think its burning oil as if it was, it would be hard to start and the plug would be caked in it.

Edited by tye1138
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Kevin Reynolds

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Tye, not to be a dick but route your breather hose to your air box like some bikes have and flip your bike upside down for a short period of time.. Then let me know if your breather hose has any oil in or not when your valve cover becomes the lowest part of the engine with a drain hose connected. I don't know if the 2009 250xcf has the breather hose connect to the air box or not. My 450's and 500 do. I know your 2013 250 does not so it your case the oil would gather in the hose and run back into the valve cover and all over the ground when flipped back upright.. All my points may very well be pointless if the 2009 breather is routed to open air like the 2013. Not knowing how many hrs are on this engine there may very well be other issues that just happen to surface during the crash, who knows I don't have the bike in front of me.. If it was my bike and the smoke didn't stop after a few run cycles I'd would do a compression check and a leak down test as Tye suggested.. If you determine it's coolant I'd pull the head..

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bbohannon

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Tye, not to be a dick but route your breather hose to your air box like some bikes have and flip your bike upside down for a short period of time.. Then let me know if your breather hose has any oil in or not when your valve cover becomes the lowest part of the engine with a drain hose connected. I don't know if the 2009 250xcf has the breather hose connect to the air box or not. My 450's and 500 do. I know your 2013 250 does not so it your case the oil would gather in the hose and run back into the valve cover and all over the ground when flipped back upright.. All my points may very well be pointless if the 2009 breather is routed to open air like the 2013. Not knowing how many hrs are on this engine there may very well be other issues that just happen to surface during the crash, who knows I don't have the bike in front of me.. If it was my bike and the smoke didn't stop after a few run cycles I'd would do a compression check and a leak down test as Tye suggested.. If you determine it's coolant I'd pull the head..

 

All great suggestions and I really appreciate the help.  The bike had 99hrs on it at the time of crash.  Top end, including cylinder, piston, and camshafts were replaced at 45 hrs.  The bike had minimal leakage past the rings when I did a leakdown on it around 55hrs.  In my opinion, the motor was in great condition

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tye1138

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My "breather hose" connects to the side of the carb just next to the airbox boot.  There was oily dirt on the side of the carb and on the bottom of the tube.  Am I on to something?

Does the breather hose connect to the valve cover?

I wonder if they run that design on the carb version of the bike only... interesting.

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Kevin Reynolds

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Bump

From the pic with the hose removed I can't tell if there is oil in that fitting and the pic of the towel looks like just oil or fuel residue mixed with dirt.. Have you had the chance to fire it up and see if it still smokes? And if you have, have you determined if it is oil smoke or coolant?

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bbohannon

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From the pic with the hose removed I can't tell if there is oil in that fitting and the pic of the towel looks like just oil or fuel residue mixed with dirt.. Have you had the chance to fire it up and see if it still smokes? And if you have, have you determined if it is oil smoke or coolant?

 

There was oil in the tube.  The rag is dirty oil that I wiped off the bottom of the tube that I believe leaked out (and also sprayed all over the carb).

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bbohannon

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So does it work better now that you cleaned out the tube?

There wasn't really a significant amount of oil in the actual tube.  I pulled the air filter and the carb did look a little greasy indicating oil did get in the intake.  I attempted to start the bike and let it idle to see if it would eventually burn up the oil and that's when I realized smoke coming out the header gasket area.  Upon further investigation, it appears there is oil leaking out of the header.  Is this burnt oil that was originally induced through the intake while it was upside down?  Is this to be of concern or should I just continue letting it idle (while dumping a huge smoke cloud) and see if it eventually gets better?  Also, the bike seems to start, idle, and rev fine.

 

I'm still injured and most likely will not be able to pull the gas tank/valve cover for another couple weeks.  However, I would like to have an idea if this is really a concern or if I should just continue with seeing if the smoke eventually subsides. 

Edited by bbohannon
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