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Discussion Starter #1
OK so I just Bought my bike yesterday . it's a 86 Vulcan 750. When I got it home and jumped the battery the bike turned over really slow and back fired After reading some threads on this site I was relieved to find out it was most likely do to the battery being bad so I bought a new battery for her and walla she fired up, but after running for about ten minute's she quit and wouldn't start up again. I got her running again today and noticed she was smoking white smoke out both exhaust pipes. Smells like it's running rich, don't smell like oil or anti freeze. She didn't quit on me today but as she warned up to normal operating temp I noticed I'll coming out of the breather case I pulled the cover and it was flooded with oil. I did some reading on here and I see that it could be that it's over full on oil so I'll be checking that after work tomorrow, my question is, is could the smoke be from it sucking oil up thru the air breather, and mixing with the gas in the carbs.... Any help would be appreciated. Thanks
 

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FREEBIRDS MC CENTRAL NY
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yup over full oil will make it smoke.check your oil for a gas smell,as you may be flooding

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OldDirtyDoc makes a great point about checking for a gasoline leak as the cause of the high oil level. Definitely want to get the carb and/or petcock fixed. Hopefully the PO was just really bad at measuring.
Also, "Voila". :)
 

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Discussion Starter #4
Thanks guys I'll definitely check that tonight when I get home if the oil smells like gas would that be from flooding the carbs or is there something else more serious going on?
 

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Or leaking through the petcock vacuum line.
 

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Agree with everyone above. A leaking petcock seal, or float valve needle will fill the crankcase with gas and cause blowback through the crankcase vent into the airbox. To be that overfilled it's unlikely that he overfilled it very likely the crankcase is flooded with gas. You can't drive it that way obviously with no lubrication, but worse the stator will get hotter and its already an issue to begin with. Drain the oil before you crank it again and check it for gas. I just went through this with my kawasaki KLX and had to rebuild the carb and petcock.
 

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When mine did it, the shifter started feeling sticky after it got good and warmed up.
 

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OK so I checked the oil it was over full I drained it down till it was half way up the check window. I thought my problem was solved, when I started it it didn't smoke I let it warm up and when I brought the idle to around to 2000 rpm, and it started smoking again and pouring oil out the left side air breather again. The oil does have a trace of gasoline smell to it but not like the oil is flooded with gas. What would make the oil come out of the air breather if the oil level is normal. I'm sure the smoking is because the oil is being pulled thru carbs and being burned. Like i said it didn't start smoking again until I brought the rpms up to around 2000 and that's when the oil started coming out the air breather again.. Thanks for all your help.
 

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I would pull the crankcase breather hose loose and see if there's a lot of positive pressure from the crankcase, at idle and revving.

Sounds like there might be a burned or broken piston/broken rings. If it's pushing oil out of the crankcase breather, it's terminal.

Does it seem to be running on one cylinder?

Otherwise, .. Raw gas getting into the pipes can cause white smoke, but it will smell like gas and not burned oil.

Gassy smelling oil has gas in it. It shouldn't be there.
 

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Check the vacuum line to the petcock, it should be dry. If it's wet with gas, petcock is leaking through.
 

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Discussion Starter #12
It seems to be running really smooth no engine noise, no back fire, smoke is white and smells like it's running rich, burns nostrils when I lean down to smell the smoke don't smell like oil burning at all. When I Rev it up it idles up smooth. Seems to be running on both cylinders. Only issue I'm having is it pulling oil from the crank case into the breather at high rpms.
 

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Discussion Starter #13
A compression test would tell me if I have bad rings correct? , what should the compression be cold engine and warmed up engine?
 

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A compression test would tell me if I have bad rings correct? , what should the compression be cold engine and warmed up engine?
Think the spec might be 130-150, not sure, but any gas engine should run on 100 psi.

If there's enough damage to cause serious blow by, a simple thumb over the spark plug hole will tell you.

It now reads like the problem is all fuel, as in way too much flooding a cylinder. Check that vacuum line, if not that, you're going to need to be inside the carbs. Find out which cylinder is getting all the extra fuel and concentrate on that carb.

The vacuum line only affects the left or front carb, if the lines are hooked up correctly. Check this first, it's easier.
 

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FREEBIRDS MC CENTRAL NY
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129-199 psi.wide open throttle when testing

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Doesn't read like compression or piston damage is the problem. I was just trying to figure a way to be pushing that much oil into the airbox. This bike isn't earshaved, I presume?

Almost has to be the petcock vacuum line feeding it, or the carb bowls are overfilling. Could be a clogged air bleed on a carb, but that's the most rare problem in this case, actually unheard of on this bike so far as we know.

So, vac line, needle valves, floats. Bad petcock diaphragm, stuck needle valve, sinking float, float height. Float height doesn't normally change on it's own, or suddenly, so that can almost be ruled out.
 

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Jd, I would still check the crankcase hose for pressure.

Even after draining the oil down to the right level, some oil left in the airbox could show up, making you think the problem is still there.

Be careful with those white gas vapors coming out of the pipes. In that form, it doesn't take much at all to ignite. For the gas to look like white smoke, it's raw, heated, and unburned fuel.
 

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Discussion Starter #18
Thank you guys for all the suggestions I'll go down the check list, I'll try to upload a video of what's going on if I'm able to.
 

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Doesn't read like compression or piston damage is the problem. I was just trying to figure a way to be pushing that much oil into the airbox. This bike isn't earshaved, I presume?

Almost has to be the petcock vacuum line feeding it, or the carb bowls are overfilling. Could be a clogged air bleed on a carb, but that's the most rare problem in this case, actually unheard of on this bike so far as we know.

So, vac line, needle valves, floats. Bad petcock diaphragm, stuck needle valve, sinking float, float height. Float height doesn't normally change on it's own, or suddenly, so that can almost be ruled out.
Even a leaking petcock will stop flow at the float needles. Overflow will be outside the engine.

Rebuild the floats, service the petcock while youre at it.
 

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FREEBIRDS MC CENTRAL NY
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no not all overflow will be outside of engine.some will also flow down the intake and through the head and fill the crankcase with oil if the float needle is sticking or if leaking through the petcock vacuum

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