Bike is blowing blue smoke

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#1
I have a '98 YZ250. it is blowing a substantial amount of blue smoke at all ranges of throttle. I am running a 32:1 ration. With the bike smoking so bad I am fouling plugs. How do I get it to stop?
 
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#3
or, more likely - carb needs tuning, but other than that 2 strokes will almost burn smoke and leave oil deposits, they need you to not putt around too much, it needs to be hot to burn off the oil, for a quick fix, go to 40:1 but that could potentially seize it if it gets too hot, so take my advice at own risk, hope this helps!
 

darringer

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#4
Check you transmission oil level. If it's low, it's the right-side crank seal letting oil into the combustion chamber, causing the overly rich mixture and excessive smoking. If, by chance, it is the carb being way rich, switching to 40:1 will make it worse, not better. When 2 strokes are running correctly they will smoke very little.
 
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#5
sharky_101 said:
or, more likely - carb needs tuning, but other than that 2 strokes will almost burn smoke and leave oil deposits, they need you to not putt around too much, it needs to be hot to burn off the oil, for a quick fix, go to 40:1 but that could potentially seize it if it gets too hot, so take my advice at own risk, hope this helps!
:coocoo: :whoa:

and 40:1 is leaner. and I dont think it's jetting if its smoking excessivly at all throttle stages but what do i know :blah:
 
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#6
changing the premix ratio from 32:1 to 40:1 would make it leaner meaning there is more fuel and less oil, as far as combustion is concerned. If it is too rich this would most likely help the problem and not make worse.
 
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#7
darringer said:
Check you transmission oil level. If it's low, it's the right-side crank seal letting oil into the combustion chamber, causing the overly rich mixture and excessive smoking. If, by chance, it is the carb being way rich, switching to 40:1 will make it worse, not better. When 2 strokes are running correctly they will smoke very little.
 
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#8
on the 250 it is also leaking excessive oil from the blow by tube when i rev it at higher rpm's does that have anything to do with it??
 
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#9
the crankcase vent tube, then your over filling it with oil. or you have a bunch of water in there, or whatever.
 

darringer

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#10
If the bike is running rich, 40:1 will make it worse than 32:1. More fuel, less oil by volume flowing through the carb will richen the jetting across the board. Generally speaking, when talking about rich/lean carb conditions, one is comparing fuel-to-air, not oil-to-air.
 
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#11
True, which is why you should not have said that a leaky seal (causing more oil in the mix) makes for an overly rich condition. If the seal is leaking, then he's burning tranny oil and making the mixture more lean.

Hope this helps.
 

darringer

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#12
Solid State. After re-reading my post you are absolutely correct. See what happens when two ideas run together simultaneously in my simple mind!