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125 sx Smoking Bad

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While riding last weekend my bike started smoking alot and smelled like something burning(not just 2 stroke oil).  I immediately turned it off.  It started right back up but was still smoking and smelled burnt.  I originally thought it was the top end, but found out that was wrong.  I asked a question on here and was told it was probably the head gasket.  Since then, I've done a little research and found out that coolant smells sweet when it burns (my exhaust smelled burnt). I did pull the head, but it was hard to tell whether the gasket was bad or not (it had a few little shred marks, but was still in one piece).  I'm starting to think it may be oil getting into the cylinder.  Does anyone know what the problem could be? I'll try to get some pics of the head/gasket tomorrow.

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if its not a head gasket then its a crank seal probably...did you lose some tranny oil?

Edited by travis1010

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I didn't check it yet but I really doubt it. It only ran at most 30 seconds after whatever went wrong happened. I was riding at top speed, probably pushing it too hard for about 20 seconds. I ordered a head gasket, so I'll start by replacing that since I already have the head off. I'll check the crankcase oil next time I have it out.

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It sounds like the wet side crank seal has failed.  When the wet side crank seal fails, the oil from your transmission gets into the combustion chamber. This is why travis1010 asked about the fluid level in the tranny.  The exhaust smell changes, as its now burning additional oil, not just the 2 stroke oil.  

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It sounds like the wet side crank seal has failed. When the wet side crank seal fails, the oil from your transmission gets into the combustion chamber. This is why travis1010 asked about the fluid level in the tranny. The exhaust smell changes, as its now burning additional oil, not just the 2 stroke oil.

That's kinda what I was thinking just wasn't sure where the oil is getting in from. How hard is it to replace the crank seal?

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Ok, right now I'm just trying to get the head put back together so I can troubleshoot from there.  The o ring I received is the wrong size.  See the picture(black=old, green=new).  Is it ok for it to be this big?  Rockymountain said they can send out another one but it will be exactly the same.  Also, does the black o ring even look bad?  There are some shreds on the sides, but it's overall intact.

oring1_zpsa67ae117.jpgoring2_zpsf9b9a551.jpg

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This one has me stumped a bit... Try putting the o-ring in the freezer for a few days and trying it again

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Did you check your plug? I had the same thing happening with my bike and it ended up being a fouled plug. It was terrible smelling white smoke and the plug was completely black

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Did you check your plug? I had the same thing happening with my bike and it ended up being a fouled plug. It was terrible smelling white smoke and the plug was completely black

Yea, the plug was very wet and black, but I didn't think that could be the only cause. 

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Yea, the plug was very wet and black, but I didn't think that could be the only cause.

idk that's what went wrong on mine but good luck! I hope you get it fixed!

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Ok, right now I'm just trying to get the head put back together so I can troubleshoot from there.  The o ring I received is the wrong size.  See the picture(black=old, green=new).  Is it ok for it to be this big?  Rockymountain said they can send out another one but it will be exactly the same.  Also, does the black o ring even look bad?  There are some shreds on the sides, but it's overall intact.

oring1_zpsa67ae117.jpgoring2_zpsf9b9a551.jpg

 

The head gasket in the second pic is the right size, just coat it in grease to help it "stick" in the groove. Most of them are like that. 

 

Also, what was on the plug? Coolant or oil?  

 

To me it sounds like you blew a trans side crank seal. 

Edited by DRZSuzook

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The head gasket in the second pic is the right size, just coat it in grease to help it "stick" in the groove. Most of them are like that. 

 

Also, what was on the plug? Coolant or oil?  

 

To me it sounds like you blew a trans side crank seal. 

So it's normal for them to be that big?  I'm not positive what was on the plug, but I think it was probably oil.  I'm starting to lean toward the crank seal being the problem.  How hard is it to replace one?

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